mud pump blows all 3 swabs free sample

A kick is a well control problem in which the pressure found within the drilled rock is higher than the mud hydrostatic pressure acting on the borehole or rock face. When this occurs, the greater formation pressure has a tendency to force formation fluids into the wellbore. This forced fluid flow is called a kick. If the flow is successfully controlled, the kick is considered to have been killed. An uncontrolled kick that increases in severity may result in what is known as a “blowout.”

Several factors affect the severity of a kick. One factor, for example, is the “permeability” of rock, which is its ability to allow fluid to move through the rock. Another factor affecting kick severity is “porosity.” Porosity measures the amount of space in the rock containing fluids. A rock with high permeability and high porosity has greater potential for a severe kick than a rock with low permeability and low porosity. For example, sandstone is considered to have greater kick potential than shale, because sandstone has greater permeability and greater porosity than shale.

Yet another factor affecting kick severity is the “pressure differential” involved. Pressure differential is the difference between the formation fluid pressure and the mud hydrostatic pressure. If the formation pressure is much greater than the hydrostatic pressure, a large negative differential pressure exists. If this negative differential pressure is coupled with high permeability and high porosity, a severe kick may occur.

If gas enters the borehole, the kick is called a "gas kick." Furthermore, if a volume of 20 bbl (3.2 m3) of gas entered the borehole, the kick could be termed a 20-bbl (3.2-m3) gas kick.

Another way of labeling kicks is by identifying the required mud weight increase necessary to control the well and kill a potential blowout. For example, if a kick required a 0.7-lbm/gal (84-kg/m3) mud weight increase to control the well, the kick could be termed a 0.7-lbm/gal (84-kg/m3) kick. It is interesting to note that an average kick requires approximately 0.5 lbm/gal (60 kg/m3), or less, mud weight increase.

Kicks occur as a result of formation pressure being greater than mud hydrostatic pressure, which causes fluids to flow from the formation into the wellbore. In almost all drilling operations, the operator attempts to maintain a hydrostatic pressure greater than formation pressure and, thus, prevent kicks; however, on occasion the formation will exceed the mud pressure and a kick will occur. Reasons for this imbalance explain the key causes of kicks:

Insufficient mud weight is the predominant cause of kicks. A permeable zone is drilled while using a mud weight that exerts less pressure than the formation pressure within the zone. Because the formation pressure exceeds the wellbore pressure, fluids begin to flow from the formation into the wellbore and the kick occurs.

These abnormal formation pressures are often associated with causes for kicks. Abnormal formation pressures are greater pressures than in normal conditions. In well control situations, formation pressures greater than normal are the biggest concern. Because a normal formation pressure is equal to a full column of native water, abnormally pressured formations exert more pressure than a full water column. If abnormally pressured formations are encountered while drilling with mud weights insufficient to control the zone, a potential kick situation has developed. Whether or not the kick occurs depends on the permeability and porosity of the rock. A number of abnormal pressure indicators can be used to estimate formation pressures so that kicks caused by insufficient mud weight are prevented (some are listed in Table 1).

An obvious solution to kicks caused by insufficient mud weights seems to be drilling with high mud weights; however, this is not always a viable solution. First, high mud weights may exceed the fracture mud weight of the formation and induce lost circulation. Second, mud weights in excess of the formation pressure may significantly reduce the penetration rates. Also, pipe sticking becomes a serious consideration when excessive mud weights are used. The best solution is to maintain a mud weight slightly greater than formation pressure until the mud weight begins to approach the fracture mud weight and, thus, requires an additional string of casing.

Improperly filling up of the hole during trips is another prominent cause of kicks. As the drillpipe is pulled out of the hole, the mud level falls because the pipe steel no longer displaces the mud. As the overall mud level decreases, the hole must be periodically filled up with mud to avoid reducing the hydrostatic pressure and, thereby, allowing a kick to occur.

Several methods can be used to fill up the hole, but each must be able to accurately measure the amount of mud required. It is not acceptable—under any condition—to allow a centrifugal pump to continuously fill up the hole from the suction pit because accurate mud-volume measurement with this sort of pump is impossible. The two acceptable methods most commonly used to maintain hole fill-up are the trip-tank method and the pump-stroke measurements method.

The trip-tank method has a calibration device that monitors the volume of mud entering the hole. The tank can be placed above the preventer to allow gravity to force mud into the annulus, or a centrifugal pump may pump mud into the annulus with the overflow returning to the trip tank. The advantages of the trip-tank method include that the hole remains full at all times, and an accurate measurement of the mud entering the hole is possible.

The other method of keeping a full hole—the pump-stroke measurement method—is to periodically fill up the hole with a positive-displacement pump. A flowline device can be installed with the positive-displacement pump to measure the pump strokes required to fill the hole. This device will automatically shut off the pump when the hole is full.

Gas-contaminated mud will occasionally cause a kick, although this is rare. The mud density reduction is usually caused by fluids from the core volume being cut and released into the mud system. As the gas is circulated to the surface, it expands and may reduce the overall hydrostatic pressure sufficient enough to allow a kick to occur.

Although the mud weight is cut severely at the surface, the hydrostatic pressure is not reduced significantly because most gas expansion occurs near the surface and not at the hole bottom.

Occasionally, kicks are caused by lost circulation. A decreased hydrostatic pressure occurs from a shorter mud column. When a kick occurs from lost circulation, the problem may become severe. A large volume of kick fluid may enter the hole before the rising mud level is observed at the surface. It is recommended that the hole be filled with some type of fluid to monitor fluid levels if lost circulation occurs.

Warning signs and possible kick indicators can be observed at the surface. Each crew member has the responsibility to recognize and interpret these signs and take proper action. All signs do not positively identify a kick; some merely warn of potential kick situations. Key warning signs to watch for include the following:

An increase in flow rate leaving the well, while pumping at a constant rate, is a primary kick indicator. The increased flow rate is interpreted as the formation aiding the rig pumps by moving fluid up the annulus and forcing formation fluids into the wellbore.

If the pit volume is not changed as a result of surface-controlled actions, an increase indicates a kick is occurring. Fluids entering the wellbore displace an equal volume of mud at the flowline, resulting in pit gain.

When the rig pumps are not moving the mud, a continued flow from the well indicates a kick is in progress. An exception is when the mud in the drillpipe is considerably heavier than in the annulus, such as in the case of a slug.

A pump pressure change may indicate a kick. Initial fluid entry into the borehole may cause the mud to flocculate and temporarily increase the pump pressure. As the flow continues, the low-density influx will displace heavier drilling fluids, and the pump pressure may begin to decrease. As the fluid in the annulus becomes less dense, the mud in the drillpipe tends to fall and pump speed may increase.

Other drilling problems may also exhibit these signs. A hole in the pipe, called a “washout,” will cause pump pressure to decrease. A twist-off of the drillstring will give the same signs. It is proper procedure, however, to check for a kick if these signs are observed.

When the drillstring is pulled out of the hole, the mud level should decrease by a volume equivalent to the removed steel. If the hole does not require the calculated volume of mud to bring the mud level back to the surface, it is assumed a kick fluid has entered the hole and partially filled the displacement volume of the drillstring. Even though gas or salt water may have entered the hole, the well may not flow until enough fluid has entered to reduce the hydrostatic pressure below the formation pressure.

Drilling fluid provides a buoyant effect to the drillstring and reduces the actual pipe weight supported by the derrick. Heavier muds have a greater buoyant force than less dense muds. When a kick occurs, and low-density formation fluids begin to enter the borehole, the buoyant force of the mud system is reduced, and the string weight observed at the surface begins to increase.

An abrupt increase in bit-penetration rate, called a “drilling break,” is a warning sign of a potential kick. A gradual increase in penetration rate is an abnormal pressure indicator, and should not be misconstrued as an abrupt rate increase.

It is recommended when a drilling break is recorded that the driller should drill 3 to 5 ft (1 to 1.5 m) into the sand and then stop to check for flowing formation fluids. Flow checks are not always performed in tophole drilling or when drilling through a series of stringers in which repetitive breaks are encountered. Unfortunately, many kicks and blowouts have occurred because of this lack of flow checking.

Fortunately, the lower mud weights from the cuttings effect are found near the surface (generally because of gas expansion), and do not appreciably reduce mud density throughout the hole. Table 3 shows that gas cutting has a very small effect on bottomhole hydrostatic pressure.

An important point to remember about gas cutting is that, if the well did not kick within the time required to drill the gas zone and circulate the gas to the surface, only a small possibility exists that it will kick. Generally, gas cutting indicates that a formation has been drilled that contains gas. It does not mean that the mud weight must be increased.

The MWD tool enables monitoring of the acoustic properties of the annulus for early gas-influx detection. Pressure pulses generated by the MWD pulser are recorded and compared at the standpipe and the top of the annulus. Full-scale testing has shown that the presence of free gas in the annulus is detected by amplitude attenuation and phase delay between the two signals. For water-based mud systems, this technique has demonstrated the capacity to consistently detect gas influxes within minutes before significant expansion occurs. Further development is currently under way to improve the system’s capability to detect gas influxes in oil-based mud.

Some MWD tools feature kick detection through ultrasonic sensors. In these systems, an ultrasonic transducer emits a signal that is reflected off the formation and back to the sensor. Small quantities of free gas significantly alter the acoustic impedance of the mud. Automatic monitoring of these signals permits detection of gas in the annulus. It should be noted that these devices only detect the presence of gas at or below the MWD tool.

The MWD tool offers kick-detection benefits, if the response time is less than the time it takes to observe the surface indicators. The tool can provide early detection of kicks and potential influxes, as well as monitor the kick-killing process. Tool response time is a function of the complexity of the MWD tool and the mode of operation. The sequence of data transmission determines the update times of each type of measurement. Many MWD tools allow for reprogramming of the update sequence while the tool is in the hole. This feature can enable the operator to increase the update frequency of critical information to meet the expected needs of the section being drilled. If the tool response time is longer than required for surface indicators to be observed, the MWD only serves as a confirmation source.

When a kick occurs, note the type of influx (gas, oil, or salt water) entering the wellbore. Remember that well-control procedures developed here are designed to kill all types of kicks safely. The formula required to make this kick influx calculation is as follows:

where gi = influx gradient, psi/ft; gmdp = mud gradient in drillpipe, psi/ft; and hi = influx height, ft. The influx gradient can be evaluated using the guidelines in Table 1.

It is necessary to calculate the mud weight needed to balance bottomhole formation pressure. “Kill-weight mud” is the amount of mud necessary to exactly balance formation pressure. It will be later shown that it is safer to use the exact required mud weight without variation

Because the drillpipe pressure has been defined as a bottomhole pressure gauge, the psidp can be used to calculate the mud weight necessary to kill the well. The kill mud formula follows:

Because the casing pressure does not appear in Eq. 2, a high casing pressure does not necessarily indicate a high kill-weight mud. The same is true for pit gain because it does not appear in Eq. 2. Example 1 uses the kill-weight mud formula.

Nas, S. 2011. Kick Detection and Well Control in a Closed Wellbore. IADC/SPE Managed Pressure Drilling and Underbalanced Operations Conference and Exhibition, 5–6 April 2011, Denver, Colorado, USA. SPE-143099-MS. http://dx.doi.org/143099-MS

Low, E. and Jansen, C. 1993. A Method for Handling Gas Kicks Safely in High-Pressure Wells. Journal of Petroleum Technology 45:6 SPE-21964-PA. http://dx.doi.org/10.2118/21964-PA

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“Once you know these (rotary screw air) compressors, they’re pretty simple,” says Garth Owens, president of Drill Tech Drilling & Pump Inc. in Chino Valley, Arizona. “It’s not rocket science, but it is a precision unit.”

With approximately 15 rotary screw air compressors (two piston booster compressors) on six drill rigs or as auxiliaries on 10 pump hoists, Owens has learned the mechanical intricacies of them. He has rebuilt the compressors, changed their gear sets, and replaced them on rigs while passing along his knowledge to others in the industry.

“A lot of guys who are drilling don’t even have the right air to develop a well and they’ll throw a pump down there and just try to pump out the mud,” says Garth’s son, Nick, the manager at Drill Tech. “It destroys pumps and you’re never getting that mud wall cake off the walls behind the gravel pack to really get what the well’s producing.”

“You can drill too big of a well to where the annulus is too big, and you can’t get through the gravel pack to get the walls clean. That’s a big problem. A lot of guys think the bigger the hole they go, the more gravel the better, which isn’t necessarily good because you can never get enough annular velocity to get through the gravel pack and get that mud cake off. So, you’ve got to step back and look at the big picture of your annulus to your casing size to your gravel pack.

“Depending on what size drill pipe, what size borehole, what that annular space is between the drill pipe and the borehole determines the amount of your cubic feet per minute,” Garth Owens explains. “And then your pressure is determined by how deep you’re going to go. Every 2.31 feet of water is one pound of pressure you have to overcome, so basically, it’s a 2-to-1 ratio.

Today’s standard rotary screw air compressor rating is at least 900 cfm or 1000 cfm/350 psi. Thirty years ago, the standard was 450 cfm/250 psi or 600 cfm/250 psi.

For example, a 750 cfm/125 psi compressor is half the compressor of a 750 cfm/250 psi compressor because the contractor is compressing the air twice as tight. Therefore, with a 750 cfm/350 psi compressor, the contractor is compressing the air an additional 50%.

To help visualize it, Garth Owens likens pressurizing the compressor to a scuba tank getting pressurized rather than simply filling a balloon with static pressure.

“Instead of putting 125 pounds in it, in order to put 250 pounds in it, it takes a bigger screw and more horsepower to do that,” he shares. “And then to go to 350, it takes a bigger compressor and more horsepower to do that. So, every compressor has two numbers—cfm, and the second number is the amount of pressure that it puts out at that number.

“For instance, for a 750/125 compressor, it’ll probably take 125 horsepower to run that. You go to 750/250, it’ll take you 300 horsepower. You go to 750/350, it’ll take 400 horsepower to do the exact same thing because you’re compressing tighter, tighter, and tighter it takes more horsepower to overcome that pressure. So, the higher the pressure, the more horsepower you need.”

“Typically, ballpark rule of thumb, standard compressor is 125 to 150 psi,” Garth Owens says. “High pressure is 175 to maybe 200 psi. Extra high pressure is usually 350 psi and the highest you’ll ever go on a screw compressor is 500 psi. That’d be extra extra high pressure to get to 500 psi. Anything after that you’re running through a piston booster compressor and boosting pressure with a piston.

“When you get into the high-pressure compressors, it takes a lot of horsepower, takes a lot of heat, it builds up a lot of heat, and it burns a lot of fuel, so if the radiators aren’t clean, if the fanbelts are slipping, if the radiator is plugged up. . . .It might run great at 250 pounds; you push it at 350 and 30 minutes later the rig is overheated.”

To decrease the uphole velocity of 3000 feet per minute, some contractors use drill foam to clean the well at half the amount, 1500 feet per minute. “If you’re using foam and you’re filling that void, you’re taking half of that void away,” Garth Owens says. “You’re using half the air because you’re filling that void with an artificial substance. It’s going to foam up and blow out and then it’s going to evaporate and go away.”

The double-swabbed tool has perforations between the two swabs. Airlifting typically occurs through the drill pipe “from which the development swabs are suspended, so as the swabbing action brings suspended solids into the well, they are purged by the simultaneous airlift system,” writes Marvin F. Glotfelty, RG, in his book, The Art of Water Wells.

“The air comes out of the end of the drill pipe, comes up and hits that rubber swab which is the same diameter as the casing,” Garth Owens says, “and therefore all that air has to go out the perforations, blows into the gravel pack, spins that around in there, and cleans the gravel pack and cleans the borehole. Then the water comes up through the gravel pack and comes back to the perforations above your swab and comes out the top of the well.”

Glotfelty writes how this well development method is effective because “it provides both inward and outward energy to break down and remove the wall cake, without forming sand bridges in the adjacent formation.”

“We’ll actually create a vacuum and pull it between sections there,” Nick Owens says. “That’s why there’s a rubber swab above and below the holes. Typically, if you want to do an air swabber, you don’t need the rubbers because you’re just blowing it out through the perforated screen into the formation.”

The company’s high-velocity horizontal jetting tools allow it to adjust the amount of air it needs to push through them. “That way it’s blowing the air through the perforated screen, through the gravel pack, and then we’re trying to develop all that mud off there if it’s a mud hole,” Nick Owens says.

The company has an additional high-velocity jetting ball tool with approximately 20 holes each drilled to 3/16 inches around it. A high-pressure pump is used to pump freshwater down the well at 2000 psi.

“That will not only churn and turn that gravel, but it places that mud thinner all the way back to the borehole to knock off the wall cake,” Garth Owens says, “and once you’re done pressure jetting it, then you’ll come back and re-swab it and RC it all back out of there.”

Drill Tech, which had a backlog of approximately 100 wells and 30 pumps to install as of late July, stresses it all starts with the design of the well, drilling it correctly, using the right products, and not overusing polymers.

“If we’re RC drilling, we’ll mud up the top and then we’ll case the top off,” Nick Owens says. “There’s some wells out here where we live where the top 300 feet is all alluvium and there’s no water in it. We’ll mud those up, we’ll set a 300-foot surface casing, and we’ll RC drill the bottom out with just pure water because it’s just solid rock. So, we don’t use any product.

“We can literally drill a 1200-foot well, pull out, put our casing in it, and gravel pack it. You can trip in as soon as we’re done with zero development and can video the well, it’s that clean. Something of that nature doesn’t take much development because we didn’t put any product in the well. It just depends on where we are.”

To drive home the importance of using the correct amount of product, Nick Owens recalls a large drilling company that installed two large municipal wells 10 years ago in central Arizona. It both drilled with and pumped too much polymer into the wells and was unable to get the polymer out. The wells produced 300 gpm.

“We drilled some other wells near them, and we got 1200 gallons per minute out of the wells and the aquifer just simply because of the development and not using polymers,” he says, “so [it’s] a big thing to make sure of the product when you’re drilling and make sure you’re using the right product that you can get back out—that’s the biggest thing.”

“Most guys will just trip their drill pipe straight in, blow it straight up the hole, and they’re done,” he shares. “But you’ll get a lot more water out of your well, you’ll pump a lot less sand, and you’ll have a much better production well with a higher pumping level if you clean that formation out and get every bit of that mud that you put in back out again. The only way to do that is with pressure through the perforations.”

While drilling in July in California, Garth Owens also noticed large amounts of gravel being put into large diameter wells drilled using the mud rotary method. “They think that the bigger the hole is, the more gravel they put in, the better it is, which is not true. What they don’t get is the bigger the hole gets, the worse development job you can do.

“Let’s say you drill a 16-inch hole and put in 6-inch casing, and you’ve got 5 inches of gravel on either side of you, you cannot get enough pressure through 5 inches of gravel to clean the wall cake off the borehole on the outside to get it to produce. The well is still going to produce, but it would be a lot better producing well if it has 2 to 3 inches of gravel and you’ve got enough energy that you can push through that.”

Low-cost gravel too has its disadvantages, with it being crushed and therefore angular. These angular pieces all wiggle together and lock together like chip seal on a highway in the well, according to Garth Owens. This causes a slowdown in the production of water.

“Most people don’t use any chemicals to break down that wall cake because it costs $250 a bucket,” he says, “so we’ll go out and drill a well that will make 500 gallons per minute, and our competition literally on the next lot is drilling 100 gallons a minute. And it’s simply because of the gravel pack and the development process.”

“Time is one factor, they want to get to the next job,” Garth Owens says. “Another factor is they don’t want to put a swab in to pressurize the perforations. The third thing is purchasing the cheapest gravel they can because they think they’re going to overcome all that by drilling a hole that’s one or two inches bigger in diameter and now all that other stuff is irrelevant.”

Install the largest gravel to have the most square inches of opening and the least friction for the water to come through but stop the finest particles of sand.

“You design with maybe a 10 percent passing of sand,” he says, “and then you want to go down there and develop it until that 10 percent gets down to 0.5 percent or 0.25 percent. You want to airlift develop that until you’ve blown out everything, you’ve agitated it, washed out the gravel, washed off the wall cake, and then the ground itself and those fines come out of there.

“If you don’t do it right, you can spend three or four days pumping sand because the gravel is too coarse. You put in too coarse of a filter and the sand just keeps flowing. It takes forever, if it ever does stop. Too coarse of a sand and it’ll never stop.”

For a high-pressure compressor, there are three gears in the bellhousing and two low-stage screws and two high-stage screws. The simplicity allows the compressor to last for an average of 10,000 hours.

“Because on a piston compressor, you just have a receiver tank that just holds air,” he says, “and you can pressure it up to 250 to 300 pounds and jerk the valve open and that big surge of air is what blows out silts and rocks when it won’t do it when steady drilling.

“On a screw compressor, when you max out the pressure at say 350 pounds, and you’ve got the same pressure inside the filter as you do on the outside of the filter, when you blast that ball valve open, the pressure differential escapes faster inside than it can equalize. That’s what causes that filter to collapse and blow all your oil down your hose. That’s the one and only thing you don’t do with a screw compressor—build up to max pressure and jerk the valve open—that you can do with a piston compressor.”

For years, automatic transmission fluid (ATF) was the standard for lubrication on compressors. Today, synthetic compressor oil is used because they must run at about 225 degrees to 275 degrees to vaporize the water as it sucks moisture out of the air when drilling. “It sucks all that moisture into it and it rusts up all the bearings and gears,” Garth Owens says, “so by turning the thermostat up so hot, it vaporizes and burns the condensation out of it.

“You hear about a lot of rigs burning down and compressors burning down, it’s typically because they have old non-synthetic oil because it costs less,” Garth Owens says. “What happens is the tolerances are very tight in a screw compressor.

“Typically, there’s three thousandths max tolerant in a screw compressor, so you really have to keep your air filters clean, your oil filters clean, and your oil good. When that tolerance starts to get loose, when you start getting a bearing wearing out or one of your screws starts wearing into the impeller of the compressor, when that tolerance starts to get loose at all, typically your oil temperatures skyrocket tremendously. It’ll run at 200 degrees for 10 years and then all of a sudden, you’re wondering why it’s running at 275 degrees and trying to cook the hoses off your rig.”

The first indication is typically losing a bearing when the oil temperature begins climbing with the tolerances getting loose. “You either have steel on steel friction, or the tolerance is so loose that after you’ve compressed this air and oil, it scoops up the air and oil and pushes it through the screw,” Garth Owens says.

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1.2 Unless the inspector and client agree to a limitation of the inspection, the inspection will be performed at the primary building and attached parking structure. Detached structures shall be inspected separately.

1.3 A mold inspection is valid for the date of the inspection and cannot predict future mold growth. Because conditions conducive to mold growth in a building can vary greatly over time, the results of a mold inspection (examination and sampling) can only be relied upon for the point in time at which the inspection was conducted.

a non-invasive visual examination of the readily accessible, visible, and installed systems and components of the building (listed in Section 4.0 Standards of Practice)

a limited non-invasive visual examination of the readily accessible, visible, and installed systems and components located only in the room or limited area (as described in previous Section 3.1).

Air sampling may be necessary if the mold growth is suspected (for example, musty odors), but cannot be identified by a visual examination. The purpose of such air sampling is to determine the location and/or extent of mold contamination as well as a simple confirmation that mold growth exists somewhere in the building. All mold spores have a source, and identifying the source is the goal.

Because the outdoor sample is the control, and it is used to compare with the indoor sample, the samples should be collected as close as possible in time and under the similar conditions. Air samples should be collected at the same air flow rate, for the same duration of time, near the same height above the floor in all rooms that are sampled indoors, and using the same type of collection device.

There are many different types of air pumps, measurement meters, and spore collectors that can be used for an air sample at a mold inspection. The air pump should be adjusted to collect air at a flow rate that is recommended by the manufacturer of the collection device.

Rotameters are air flow meters that provide field accuracy in an easy-to-read instrument. The principle of operation is simple: air flow passes through a vertical, tapered tube and pushes a small ball or float having a diameter slightly less than the smaller tube end. As the little ball rises, the clearance between the ball and the tube wall increases. The ball becomes stationary when the diameter of the tube is large enough to allow the total airflow past the ball. The flow rate is determined by reading the number on the tube at the middle position of the stabilized ball.

If there is an area of concern (a room or area with moisture intrusion, water damage, musty odors, apparent mold growth, or conditions conducive to mold growth), the inspector shall perform at least one (1) surface sample in EACH area of concern.

Inspector shall take at least one (1) swab sample when a visual examination of the building yields moisture intrusion, water damage, apparent mold growth, musty odors, or conditions conducive to mold growth. Additional sampling may be performed at the discretion of the inspector.

In general, an inspector will typically hold the tube container so that the ampoule with the liquid preservative is at the top. You pinch the plastic tube so the liquid will flow down onto the swab. To remove the moistened swab, you pull on the cap. Rub and roll the wet swab over a one-inch square area of the apparent mold growth. The swab should collect visible apparent mold. Insert the swab back into the tube. Secure the cap.

If mold is visible on different substrates or building materials such as wood, drywall, or wallpaper, then a sample from each different material is recommended.

One of the most popular tape sampling products is the Bio-Tape™ system. There are many advantages of using tape lift systems such as the Bio-Tape™ instead of using regular tape. Bio-Tape™ is easier to handle, the tapes are individually numbered, it requires less laboratory preparation time, and the slides are flexible and will not break.

If mold is visible on different substrates or building materials such as wood, drywall, or wallpaper, then a tape sample from each different material is recommended.

A household vacuum machine and a carpet-sampling cartridge are used to vacuum a small area of the carpet. The cartridge should be inserted as deep into the pile of the carpet as possible. If a carpet has not been cleaned thoroughly prior to a sampling, a carpet can easily hold evidence of a mold problem in the house. Even after cleaning, there can be mold spores discovered deep in the carpet.

Choose a 6-foot by 3-foot sampling area in front of the sofa or large chair where occupants spend a lot of time. Vacuum this area thoroughly. Next select a 6-foot by 3-foot area in a bedroom along side a bed. Remove filter. Place into the bag that came with the unit. Mail it to the laboratory.

The inspector shall perform two (2) outdoor samples of the highest quality general air to be used as control samples (or background samples). These samples to be used for comparison with the indoor sample(s).

The outdoor sampling should begin soon after arriving at the property, assuming that the weather is clean and calm. It is better for an inspector to perform the outdoor sampling while the weather is favorable than to wait. The outdoor conditions may change drastically during the examination and sampling of the building interior.

Air sampling should not be conducted during unusually severe storms or periods of unusually high winds. Severe weather will affect the sampling and analysis results in several ways.

On a Chain-of-Custody form, the weather conditions shall be recorded. The weather conditions should be clean and calm. High winds may affect the quality of the sampling, including the comparison between indoor and outdoor sampling.

Air pump sampling should not take place outdoors if it is raining. If possible, you should wait for at least two (2) hours after the rain has stopped before taking an air pump sample. Alterations or adjustments to the normal procedure or locations of taking air pump samples, particularly for the control sample, must be recorded in a Chain-of-Custody.

Air pump sampling should not take place when the outdoor air temperature is below 32° Fahrenheit. All air sampling should take place when the air temperature is above freezing.

If the ground is completely covered with snow, outdoor air pump sampling should not be performed. A partial covering or a light dusting of snow is acceptable.

On a clean windless day, air pump sampling should run for 10 minutes. (Be sure to refer to the manufacturer’s recommendation. There are cassettes that require only 5 minutes such as the Z5.) When the outdoor air is something other than clean and windless, then the time of the sampling should be reduced to 5 minutes or less. A breeze, the mowing of grass, nearby construction, and dusty air all affect the sampling conditions.

If possible, one outdoor sample should be located on the windward side of the building (the side facing the point from which the wind blows), and the other should be located on the leeward-side of the building (the side sheltered from the wind).

The sampling device located on the windward side of the building should be positioned so as to face the wind directly. The sampling device should point towards the wind, in the direction of the point from which the wind is blowing. The sampling device should be three to six feet (3-6 ft.) from the ground surface (breathable space).

Typically the device is about 10 feet away from the front entry door. The idea is to have both outdoor samples located in areas where the devices will collect a representative sampling of the air that may enter the building through the entry door or nearby open windows (the openings on the sides of the building).

The air sampling devices should be kept at least ten feet (10 ft.) away from all openings, air intakes, registers, exhaust vents, vent pipes, ventilation fans, etc.

Windows on all levels and external doors should be kept closed (except during normal entry and exit) during the sampling period. Normal entry and exit include a brief opening and closing of a door, but–to the extent possible–external doors should not be left open for more than a few minutes.

Normal operation of permanently installed energy recovery ventilators (also known as heat recovery ventilators or air-to-air heat exchangers) may also continue during closed-building conditions. In houses where permanent radon mitigation systems have been installed, these systems should be functioning during the air-sampling period.

Closed-building conditions will generally exist as normal living conditions in northern areas of the country when the average daily temperature is low enough so that windows are kept closed. Depending on the geographical area, this can be the period from late fall to early spring.

At least one (1) air sampling shall be taken at an air supply register of the HVAC system. It is preferred to sample prior and during the operation of the HVAC system. If only one sampling can be performed, then the sampling should be taken 15 minutes after the HVAC system is turned on.

Ideally, there would be at least three sampling devices similarly situated throughout the building, but financial or time constraints may limit the number of samples that can be taken.

The air sample should be taken three to five feet (3-5 ft.) from an air supply register, with the sampling device oriented so that air from the supply register directly enters the sampling device.

At least one (1) air sample shall be taken near the center of EACH room or area of the building in which there are areas of concern (moisture intrusion, water damage, musty odors, visible apparent mold growth, and conditions conducive to mold growth).

At least one (1) indoor air sample shall be taken in the most lived-in common room, such as the family, living, or entertainment room (The location shall be determined at the discretion of the inspector).

Inside the building, the air pump sampling should run for 10 minutes. If there is a lot of indoor activity, then the air pump sampling should be reduced to 5 minutes. If there is an active source of dust, such as construction or cleaning, then the air sampling time should be reduced to 1 minute. Be sure to follow the recommendations of the manufacturer of the sampling device or collector; there are some devices that are designed to take a sample in 5 mintues (i.e. Z5 cassette).

The sampling equipment must be protected, clean, and properly maintained at all times. The sampling device shall be clean, free from dirt or debris prior to starting a sample. If re-usable collection devices are used, then they shall be handled and cleaned prior to use in accordance with the manufacturer’s recommendation. The collector may re-usable and have sticky slides already prepared, or the collector may be a one-time-use self-contained device.

Slides, cassettes, and one-time-use devices should be stored in cool, dry environments. The slides must be protected from direct sunlight. Sampling devices (slides, swabs, cassettes, tapes) older than one year should not be used.

Set the air collector at a normal breathing height, which is about 3 to 6 feet above the ground level or floor surface. A tripod is typically used to set the collector height.

Calibrate the flow of the pump. Do not attach the sampling device, cassette or collector on the tubing yet. Measure the flow rate of the pump with a rotameter that has been calibrated to a standard. Make sure that the flow rate is set to the manufacturer’s recommendation. For example, an Air-O-Cell cassette flow rate is 15 liters of air per minute. The pump should be calibrated regularly (once a day). A record of calibrations should be kept in a work ledger or logbook.

After turning on the air pump, check the airflow rate. The flow rate should not vary. A flow change greater than five percent (5%) requires a new air sample to be taken. All air samples must have the same volume. A digital time controller on the equipment is highly recommended.

Remember, all air samples must have the same volume. Refer to manufacturer’s recommendations about sampling time and volume for each type of sampling device.

Place slides in a protective carrying case. Or close the collector if a cassette is used. A new sample must be taken, if a slide is accidentally touched, smeared, or contaminated, because it will be unreadable.

Calculate the volume by multiplying the liters of air pumped by the number of minutes. An example of the calculation is 20 liters of air pump multiplied by 10 minutes equals 20 liters per minute equals 200 liters (20L x 10 minutes = 200 L).

G. Move any personal items or other inspection obstructions, such as, but not limited to: insulation, throw rugs, furniture, floor or wall coverings, ceiling tiles, window coverings, equipment, plants, ice, debris, snow, water, dirt, foliage, or appliances.

7.3 Area of Concern: A room or area with moisture intrusion, water damage, musty odors, visible apparent mold growth, and conditions conducive to mold growth.

7.7 Dismantle: To open, take apart or remove any component, device or piece that would not typically be opened, taken apart or removed by an ordinary occupant.

7.22 Inspect(ed): To visually look at readily accessible systems and components safely, using normal operating controls and accessing readily accessible panels and areas in accordance with these Standards of Practice.

7.25 Technically Exhaustive: A comprehensive and detailed examination beyond the scope of a mold inspection which would involve or include, but would not be limited to: dismantling, specialized knowledge or training, special equipment, measurements, calculations, testing, research, analysis or other means.

7.26 Unsafe: A condition in a readily accessible, installed system or component, which is judged to be a significant risk of personal injury during normal, day-to-day use. The risk may be due to damage, deterioration, improper installation or a change in accepted residential construction standards

1.2 Unless the inspector and client agree to a limitation of the inspection, the inspection will be performed at the primary building and attached parking structure. Detached structures shall be inspected separately.

1.3 A mold inspection is valid for the date of the inspection and cannot predict future mold growth. Because conditions conducive to mold growth in a building can vary greatly over time, the results of a mold inspection (examination and sampling) can only be relied upon for the point in time at which the inspection was conducted.

2.1 The inspector shall perform:a non-invasive visual examination of the readily accessible, visible, and installed systems and components of the building (listed in Section 4.0 Standards of Practice)

3.2 The inspector shall perform:a limited non-invasive visual examination of the readily accessible, visible, and installed systems and components located only in the room or limited area (as described in previous Section 3.1).

Air sampling may be necessary if the mold growth is suspected (for example, musty odors), but cannot be identified by a visual examination. The purpose of such air sampling is to determine the location and/or extent of mold contamination as well as a simple confirmation that mold growth exists somewhere in the building. All mold spores have a source, and identifying the source is the goal.

Because the outdoor sample is the control, and it is used to compare with the indoor sample, the samples should be collected as close as possible in time and under the similar conditions. Air samples should be collected at the same air flow rate, for the same duration of time, near the same height above the floor in all rooms that are sampled indoors, and using the same type of collection device.

5.2 Air Flow RateThere are many different types of air pumps, measurement meters, and spore collectors that can be used for an air sample at a mold inspection. The air pump should be adjusted to collect air at a flow rate that is recommended by the manufacturer of the collection device.

5.3 RotameterRotameters are air flow meters that provide field accuracy in an easy-to-read instrument. The principle of operation is simple: air flow passes through a vertical, tapered tube and pushes a small ball or float having a diameter slightly less than the smaller tube end. As the little ball rises, the clearance between the ball and the tube wall increases. The ball becomes stationary when the diameter of the tube is large enough to allow the total airflow past the ball. The flow rate is determined by reading the number on the tube at the middle position of the stabilized ball.

5.4.1 Area of Concern – Take One SampleIf there is an area of concern (a room or area with moisture intrusion, water damage, musty odors, apparent mold growth, or conditions conducive to mold growth), the inspector shall perform at least one (1) surface sample in EACH area of concern.

5.4.3 SwabA swab comes inside a plastic tube container. The cellulose swab is moistened with a liquid preservative stored in an ampoule at one end of the tube container. Any bacteria collected with the swab are transferred via the swab into a tube. The tube is sent directly to a laboratory for analysis.

5.4.3.1 Areas of ConcernInspector shall take at least one (1) swab sample when a visual examination of the building yields moisture intrusion, water damage, apparent mold growth, musty odors, or conditions conducive to mold growth. Additional sampling may be performed at the discretion of the inspector.

5.4.3.2 SamplingIn general, an inspector will typically hold the tube container so that the ampoule with the liquid preservative is at the top. You pinch the plastic tube so the liquid will flow down onto the swab. To remove the moistened swab, you pull on the cap. Rub and roll the wet swab over a one-inch square area of the apparent mold growth. The swab should collect visible apparent mold. Insert the swab back into the tube. Secure the cap.

5.4.3.3 Each SampleA unique sample number should be recorded for each swab sample. Write the number on the tube itself. The Chain-of-Custody document should have the sample number, location, date, and time of the sampling.

5.4.3.5 Each ColorIf there is apparent mold growth with different colors in the room or area, take a sample of each different colored mold. The different colors may indicate different mold types.

5.4.3.6 Each SubstrateIf mold is visible on different substrates or building materials such as wood, drywall, or wallpaper, then a sample from each different material is recommended.

One of the most popular tape sampling products is the Bio-Tape™ system. There are many advantages of using tape lift systems such as the Bio-Tape™ instead of using regular tape. Bio-Tape™ is easier to handle, the tapes are individually numbered, it requires less laboratory preparation time, and the slides are flexible and will not break.

5.4.4.3 Each SampleA unique sample number should be recorded for each tape sample. The Chain-of-Custody document should have the sample number, location, date, and time of the tape sampling.

5.4.4.6 Each SubstrateIf mold is visible on different substrates or building materials such as wood, drywall, or wallpaper, then a tape sample from each different material is recommended.

A household vacuum machine and a carpet-sampling cartridge are used to vacuum a small area of the carpet. The cartridge should be inserted as deep into the pile of the carpet as possible. If a carpet has not been cleaned thoroughly prior to a sampling, a carpet can easily hold evidence of a mold problem in the house. Even after cleaning, there can be mold spores discovered deep in the carpet.

5.4.5.2 SamplingChoose a 6-foot by 3-foot sampling area in front of the sofa or large chair where occupants spend a lot of time. Vacuum this area thoroughly. Next select a 6-foot by 3-foot area in a bedroom along side a bed. Remove filter. Place into the bag that came with the unit. Mail it to the laboratory.

5.5.1 Two Outdoor SamplesThe inspector shall perform two (2) outdoor samples of the highest quality general air to be used as control samples (or background samples). These samples to be used for comparison with the indoor sample(s).

5.5.2 Upon ArrivalThe outdoor sampling should begin soon after arriving at the property, assuming that the weather is clean and calm. It is better for an inspector to perform the outdoor sampling while the weather is favorable than to wait. The outdoor conditions may change drastically during the examination and sampling of the building interior.

5.5.3 WeatherAir sampling should not be conducted during unusually severe storms or periods of unusually high winds. Severe weather will affect the sampling and analysis results in several ways.

5.5.3.1 Clean and CalmOn a Chain-of-Custody form, the weather conditions shall be recorded. The weather conditions should be clean and calm. High winds may affect the quality of the sampling, including the comparison between indoor and outdoor sampling.

5.5.3.2 No RainAir pump sampling should not take place outdoors if it is raining. If possible, you should wait for at least two (2) hours after the rain has stopped before taking an air pump sample. Alterations or adjustments to the normal procedure or locations of taking air pump samples, particularly for the control sample, must be recorded in a Chain-of-Custody.

5.5.3.3 Above FreezingAir pump sampling should not take place when the outdoor air temperature is below 32° Fahrenheit. All air sampling should take place when the air temperature is above freezing.

5.5.3.4 No snow coveringIf the ground is completely covered with snow, outdoor air pump sampling should not be performed. A partial covering or a light dusting of snow is acceptable.

5.5.3.5 Ten MinutesOn a clean windless day, air pump sampling should run for 10 minutes. (Be sure to refer to the manufacturer’s recommendation. There are cassettes that require only 5 minutes such as the Z5.) When the outdoor air is something other than clean and windless, then the time of the sampling should be reduced to 5 minutes or less. A breeze, the mowing of grass, nearby construction, and dusty air all affect the sampling conditions.

5.5.4 LocationIf possible, one outdoor sample should be located on the windward side of the building (the side facing the point from which the wind blows), and the other should be located on the leeward-side of the building (the side sheltered from the wind).

The sampling device located on the windward side of the building should be positioned so as to face the wind directly. The sampling device should point towards the wind, in the direction of the point from which the wind is blowing. The sampling device should be three to six feet (3-6 ft.) from the ground surface (breathable space).

Typically the device is about 10 feet away from the front entry door. The idea is to have both outdoor samples located in areas where the devices will collect a representative sampling of the air that may enter the building through the entry door or nearby open windows (the openings on the sides of the building).

The air sampling devices should be kept at least ten feet (10 ft.) away from all openings, air intakes, registers, exhaust vents, vent pipes, ventilation fans, etc.

Windows on all levels and external doors should be kept closed (except during normal entry and exit) during the sampling period. Normal entry and exit include a brief opening and closing of a door, but–to the extent possible–external doors should not be left open for more than a few minutes.

Normal operation of permanently installed energy recovery ventilators (also known as heat recovery ventilators or air-to-air heat exchangers) may also continue during closed-building conditions. In houses where permanent radon mitigation systems have been installed, these systems should be functioning during the air-sampling period.

Closed-building conditions will generally exist as normal living conditions in northern areas of the country when the average daily temperature is low enough so that windows are kept closed. Depending on the geographical area, this can be the period from late fall to early spring.

5.6.2.1 Take One Air SampleAt least one (1) air sampling shall be taken at an air supply register of the HVAC system. It is preferred to sample prior and during the operation of the HVAC system. If only one sampling can be performed, then the sampling should be taken 15 minutes after the HVAC system is turned on.

Ideally, there would be at least three sampling devices similarly situated throughout the building, but financial or time constraints may limit the number of samples that can be taken.

5.6.2.3 LocationThe air sample should be taken three to five feet (3-5 ft.) from an air supply register, with the sampling device oriented so that air from the supply register directly enters the sampling device.

5.6.3.1 Take One Air SampleThe inspector shall perform at least one (1) indoor sample. Additional samples may be performed at the discretion of the inspector.

5.6.3.2 Areas of ConcernAt least one (1) air sample shall be taken near the center of EACH room or area of the building in which there are areas of concern (moisture intrusion, water damage, musty odors, visible apparent mold growth, and conditions conducive to mold growth).

5.6.3.3 No Areas of ConcernAt least one (1) indoor air sample shall be taken in the most lived-in common room, such as the family, living, or entertainment room (The location shall be determined at the discretion of the inspector).

5.6.3.4 LocationAn indoor air sampling should only take place in a livable space in the building. Sampling in areas such as closets, under-floor crawlspaces, unfinished attics, storage or utility rooms, or inside the HVAC system is prohibited.

5.6.3.5 Ten MinutesInside the building, the air pump sampling should run for 10 minutes. If there is a lot of indoor activity, then the air pump sampling should be reduced to 5 minutes. If there is an active source of dust, such as construction or cleaning, then the air sampling time should be reduced to 1 minute. Be sure to follow the recommendations of the manufacturer of the sampling device or collector; there are some devices that are designed to take a sample in 5 mintues (i.e. Z5 cassette).

5.6.4 SamplingThe sampling equipment must be protected, clean, and properly maintained at all times. The sampling device shall be clean, free from dirt or debris prior to starting a sample. If re-usable collection devices are used, then they shall be handled and cleaned prior to use in accordance with the manufacturer’s recommendation. The collector may re-usable and have sticky slides already prepared, or the collector may be a one-time-use self-contained device.

Slides, cassettes, and one-time-use devices should be stored in cool, dry environments. The slides must be protected from direct sunlight. Sampling devices (slides, swabs, cassettes, tapes) older than one year should not be used.

Set the air collector at a normal breathing height, which is about 3 to 6 feet above the ground level or floor surface. A tripod is typically used to set the collector height.

Calibrate the flow of the pump. Do not attach the sampling device, cassette or collector on the tubing yet. Measure the flow rate of the pump with a rotameter that has been calibrated to a standard. Make sure that the flow rate is set to the manufacturer’s recommendation. For example, an Air-O-Cell cassette flow rate is 15 liters of air per minute. The pump should be calibrated regularly (once a day). A record of calibrations should be kept in a work ledger or logbook.

After turning on the air pump, check the airflow rate. The flow rate should not vary. A flow change greater than five percent (5%) requires a new air sample to be taken. All air samples must have the same volume. A digital time controller on the equipment is highly recommended.

Remember, all air samples must have the same volume. Refer to manufacturer’s recommendations about sampling time and volume for each type of sampling device.

Place slides in a protective carrying case. Or close the collector if a cassette is used. A new sample must be taken, if a slide is accidentally touched, smeared, or contaminated, because it will be unreadable.

Calculate the volume by multiplying the liters of air pumped by the number of minutes. An example of the calculation is 20 liters of air pump multiplied by 10 minutes equals 20 liters per minute equals 200 liters (20L x 10 minutes = 200 L).

G. Move any personal items or other inspection obstructions, such as, but not limited to: insulation, throw rugs, furniture, floor or wall coverings, ceiling tiles, window coverings, equipment, plants, ice, debris, snow, water, dirt, foliage, or appliances.

7.3 Area of Concern: A room or area with moisture intrusion, water damage, musty odors, visible apparent mold growth, and conditions conducive to mold growth.

7.7 Dismantle: To open, take apart or remove any component, device or piece that would not typically be opened, taken apart or removed by an ordinary occupant.

7.22 Inspect(ed): To visually look at readily accessible systems and components safely, using normal operating controls and accessing readily accessible panels and areas in accordance with these Standards of Practice.

7.25 Technically Exhaustive: A comprehensive and detailed examination beyond the scope of a mold inspection which would involve or include, but would not be limited to: dismantling, specialized knowledge or training, special equipment, measurements, calculations, testing, research, analysis or other means.

7.26 Unsafe: A condition in a readily accessible, installed system or component, which is judged to be a significant risk of personal injury during normal, day-to-day use. The risk may be due to damage, deterioration, improper installation or a change in accepted residential construction standards