oil burner safety valve free sample

In our oil safety valve photo at page top the OSV is in the OPEN position - the telltale indicator is that the screw is visible protruding up through the top of the silver-gray valve handle.

Fusible-link oil line valves such as the Fire-o-Matic valve work opposite from usual plumbing valves - that is, internally, because of the "reverse-threaded" valve stem, these oil line control and safety valves seem to operate backwards from what you"d expect.

To Open the OSV - let oil flow: turn the oil line valve counter-clockwise (left to right - in the direction of my finger to OPEN heating oil fuel flow. The threadsOn this part are cut opposite from usual plumbing shutoff valves. As you turn the valve handwheel in this direction the threaded valve stem will protrude upwards through the rotating knob. Oil will flow when the valve is open. In my photo the valve was about half-way open.

When the valve stem protrudes fully up through the turn-knob as far as possible you have compressed an internal spring inside the valve, and the valve is open to let oil flow. The handwheel actually feels "tighter" (as you are compressing the spring) and the handwheel moves down against the valve body as the valve opens.

To Close the OSV - stop oil flow: rn the Firematic type OSV clockwise (right to left) to close the valve and stop oil flow. As you turn the valve handwheel or knob in this direction (opposite to the direction my finger is pointing) the valve stem will disappear down into the valve body, pushed by its internal spring. You are closing the valve - oil will not flow.

When the turn knob is rotated so that the valve stem moves down through the knob until the stem end is flush with the knob top and the knob is loose, the valve is fully closed and oil will not flow.

Watch out: if the control valve on a heating oil line is not a fusible-link safety valve such as the Fire-o-Matic™, it will probably be an ordinary plumbing stop valve that works as all plumbing valves:clockwise closes those valves by moving the valve stem down and counter-clockwise to move the valvestem up opens them. Sometimes we find a common stop valve on the oil line at the oil tank and a fusible-link safety valve just at each oil burner.

An internal spring pressure, combined with a fusible link in the valve stem are what shut the oil line valve in event of a fire. In this design, when the valve is open to permit heating oil to flow it is also under spring tension. Because the valve includes a fusible link, in event of a fire the fusible link melts and the internal spring pushes the valve stem down, closing the valve and stopping oil flow.

As you turn the handle on the oil piping safety valve counter-clockwise you will feel increasing spring tension as you are opening the valve (lifting the stem out of the valve body) against the spring pressure.

Because of the use of "reverse" threads on the valve stem, when you turn the OSV knob counter-clockwise the underside of the control knob, remaining in contact with the surface of the valve body, causes the valve stem to move up (against pressure of the valve"s internal spring) until the threaded stem protrudes fully through the knob and you cannot turn the knob any more. In my photo the valve is about half-way open.

When the valve is fully open to permit fuel flow, the valve stem is "all the way out" of the valve body and the valve is being pushed-on by the internal spring. In this position the valve"s knob has been turned clockwise, all the way down against the body of the valve.

When this oil line fusible-link valve is completely open to heating oil fuel flow, the valve stem is screwed all the way up "out" of the valve body. As you turn the valve knob clockwise you"ll feel it moving against the internal valve spring pressure and you will see the valve stem moving up and out through the center of the oil valve knob.

When the oil safety valve handle is screwed clockwise (right to left) so that the threaded rod has disappeared fully down into the valve body the valve handle will become loose and the valve internal components will be in the closed position - heating oil fuel will not flow.

Because of the use of "reverse threads" on the valve stem, when you turn the OSV knob clockwise , as the knob itself remains in contact with the valve body, the spring-loaded valve stem will move down into the valve body, closing off the oil flow.

As you turn the oil valve knob clockwise you will see the valve stem move back into the valve body and you will feel the spring tension on the device lessen.

For the last few counter-clockwise turns on the valve stem/screw you should feel a complete release of tension of the spring mentioned just above and if you keep turning the valve knob counter-clockwise it will unscrew and come off. Don"t panic if this happens. The threaded portion of the valve stem protrudes up through the valve body and you can simply screw the knob back on.

In our OSV photos below, the first photo (below left) shows the oil line safety valve in the OPEN positin - oil will flow when the threaded portion of the valve shaft extends fully up through the rotatable knob pointed to by my pencil.

In our heating oil line valve photo at above right the valve has been manually CLOSED - no oil will flow. The threaded valve stem has disappeared down into the valve body and has shut off the valve and oil flow.

Watch out: if (for example in case of a fire) the fusible link inside of an OSV has melted permitting the spring to close the valve, then from outside the valve may look as if it is in the open position - the threaded stem will still be poking out - but the valve has snapped and closed internally.

Put another way: if you turn the oil line valve until the handle begins to come off, the valve is in the CLOSED position. You will see that at this point you have removed all tension against the valve"s internal spring and the spring has pushed the valve shut or closed. The valve stem has moved into the valve body.

If you turn the valve against its spring tension the valve is in its OPEN position. You will see that in this position you have turned the valve against its spring tension - the spring tension is increased - and the valve is open. The valve stem has moved out of the valve body.

at OIL FILTERS on HEATING EQUIPMENT where during heating equipment oil filter servicing the valve is used to close and later open the oil line feeding the oil burner

Thanks so much; what a great way to remember which way to turn the fire-o-matic valve stem: NO STEM = NO OIL - if you don"t see the valve stem poking up through the knob then the valve has been closed.

This is such a helpful article ! Thank you . After reading it I"ve concluded - " no stem , no oil " so I just remember that as I gently turn the valve handle ;

but there is also an air bleeding procedure used by a service tech right on the fuel unit itself. That procedure will eventually remove all of the air from the filter and piping provided that there are no leaky fittings. But in my training we learned to first bleed at the filter manually, probably just to get a big part of the air out of the system first, avoiding having to keep forcing the burner to run without ignition (that"s potentially dangerous).

Watch out: if you are not trained and familiar with how to perform all of those steps correctly you risk not only poor oil burner operation but a possible puffback explosion that can be caused by leaving air in the oil system or by an improperly-adjusted oil burner. In the old days we could "tune" an oil burner by eye and a bit of spit but modern high speed burners need to be adjusted using training and equipment such as CO2 or O2 measurement, smoke measurement, draft measurement, and temperature measurement.

What"s the best way to bleed out the air from the filter? I"ve bled the burner which is after the filter, should I also bleed the filter/filter housing as well by getting the furnace to call for oil, or does bleeding the burner essentially take out any air in the loop?

Thanks! I kind of freaked out a bit after changing the filter wondering why when i opened the valve no oil was coming through. I thought I just turned my dollar saving filter changing exercise into an expensive service call....

In a two-line oil pipe system one line supplies oil to the fuel unit and the other is a return back to the oil tank. On that installation you to actually C300 oil pipes the supply of oil coming in through the filter, the return line to the tank, and a smaller-diameter high pressure line that feeds oil at high pressure out of the fuel unit and into the oil burner.

My point about tank elevation was that It"s Perfectly Natural that if the take oil height is not above the height of the fuel unit you won"t feed oil by gravity to the fuel unit but when the unit runs is perfectly capable of lifting oil, typically up about 6 feet at Max, or lifting even higher in a two line system.

Sorry forgot to add yes I have turned the valve completely counterclockwise all the way to the point it does move anymore and the stem is fully exposed. I"ve also turned the furnace on and bled the burner so it appears that there is absolutely oil going thru the lines when the furnace is calling.

I believe it is tank->supply line-> OSV -> in to filter -> out to the burner, then another line that appears to go out (which seems to me to be a 2 line?), no other valves in that setup that I saw.

My valve looks the same as this but when it is in the Open position it doesn"t seem that oil flows through on it"s own, but when I turn the boiler on and there is a call for oil it is definitely going through. I discovered this as I went to change the filter and wanted to open the valve to release any air that may have been in the line, but with the valve open no oil was flowing, only when the boiler is on and calls. Is there something special about how this has been setup that it would do this?

So....left to right is CLOCKWISE,,,,,right to left is COUNTERCLOCKWISE.....to CLOSE the valve you rotate counterclockwise and allow the inner spring to close the valve. To OPEN the valve you would rotate clockwise and provide a counterbalance to the spring.

Sometimes a valve is loosened so as to allow the valve spring to close the valve but the valve sticks. A technician might tap gently on the valve stem to be sure it"s fully CLOSED.

These oil valve turned in the opposite direction from that to which you are accustomed. It sounds as though you were turning off the oil flow to your burner. That"s why the burner goes off.

Counter-clockwise turning of the handwheel on an OSV feels as if you are "tightening" the valve and the valve stem moves "up" through the handwheel - fully CCW opens the valve and oil can flow. The valve stem is "reverse threaded" compared with normal plumbing valves.

I think you"ve got your open and closed backwards, you seem to say the same thing for both normal valves and firematic valves ( See under watch out Clock wise is open ccw is closed ?) Confusing. While under summary, you have it correct.

Watch out: if you break it off you"ll have a financially ruinous oil tank flood in your home so take great care. If some fool does snap off an oil valve and can"t otherwise shut off oil flowing from an above ground oil tank, for an emergency repair just bent and crimp the copper tubing to stop the oil flow.

You describe an irritating problem indeed. If the oil safety valve simply won"t close you"re at least lucky to continue to have heat. The solution is to use up oil in the tank, have its remains pumped out, then replace the valve.

- the line is cut near the oil tank (or near the oil burner where an OSV valve should be anyway) and a second new working valve is installed on the lines.

I suppose a very confident plumber with help from an assistant might try putting down a pan, trying to fix the valve while spilling oil, but given the trouble of cleaning up an oil spill that live approach makes me nervous.

I haven"t seen it used on an oil line and there might be problems, but plumbers also use a heat soluble plug that can be jammed into a pipe to permit repairs, then dissolving the plug with heat.

Question: I have a fire-O-matic valve attached directly to the oil tank: it"s now open and the furnace is running fine. I would like to close the valve and replace the downstream filter element. But when I turn the handle in either direction the stem turns with the handle..

.in other words, I cannot close the valve. I"ve tried the tapping on the end of the stem approach mentioned in the stuck valve section, but to no avail.

"When the valve is fully open to permit fuel flow, the valve stem is "all the way out" of the valve body and the valve is being pushed-on by the internal spring. In this position the valve"s knob has been turned clockwise, all the way down against the body of the valve.

When this oil line fusible-link valve is completely open to heating oil fuel flow, the valve stem is screwed all the way up "out" of the valve body. As you turn the valve knob clockwise you"ll feel it moving against the internal valve spring pressure and you will see the valve stem moving up and out through the center of the oil valve knob."

In both of these paragraphs the use of the word clockwise should be replaced with the word Counter-clockwise. I know this is just a typo but it will be very confusing to someone who is not familiar with these valves. It"s hard enough for people to understand without adding typos to the mix. Other than this thank you for publishing an excellent article.

If you have a fusible link valve that doesn"t seem to turn off you might try tapping the exposed end of the valve stem. I have found a stuck, or slow to close OSV on a few rare occasions. A gentle tap, not hard enough to damage threads, loosens it after which I open and close the valve a few times to convince myself it now moves freely. A burr on the brass interior or more likely internal sludge or debris could be the culprit.

Because at the oil burner the OSV is likely to be used at least once a year during service, that"s a good opportunity to discover if the valve is not closing fully.

What is the difference among all these different kinds of valves used on oil piping and at the oil burner or oil tank: check valve, fusible link valve, fire-o-matic type valve, vacuum operated valves, quickstop valves, solenoid valves, and oil delay valves. It"s really confusing.

We agree that there are enough valves and enough similarity in their names that the controls used at oil tanks, on oil piping, and at the oil burner to manage the flow of oil can be confusing. Worse, valves that do different things and have different purposes may all be called "oil safety valves" in marketing and technical literature.

Don"t confuse the built-in check valve in the fuel unit with external check valves, fusible link oil safety valves, solenoid operated quick-stop oil valves, and their sisters, solenoid operated oil delay valves.

OIL LINE SAFETY VALVE TURN DIRECTION to OPEN or SHUT at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

[1]AUDELS OIL BURNER GUIDE, INSTALLING, SERVICING, REPAIRING, [PDF online copy of this book] Frank D. Graham, Theo. Audel & Co., New York 1946, 1947, 1955 (out of print, copies occasionally available from antique book dealers and on EBay). Use THIS LINK to read a free online copy of this helpful classic textbook.

[2] Beckett Model SR Oil Burner Instruction Manual, R.W. Beckett Corporation, PO Box 1289, Elyria OH 44036 and R.W. Beckett Canada, Ltd., 430 Laird St., Guelph, Ontario, Canada N1G 3x7

[3] Thanks to Bottini Fuel service tecnician Bob for discussing the buzzing aquastat relay problem, 4/18/2012. Bottini Fuel is a residential and commercial heating oil distributor and oil heat service company in Wappingers Falls, NY and with offices in other New York locations. Bottini Fuel, 2785 W Main St, Wappingers Falls NY, 12590-1576 (845) 297-5580 more contact information for Bottini Fuel

e-Mail : information@suntec.fr, [copy on file as /heating/Oil pumps fuel units/Form 2155 - PRV-38 Installation.pdf]. You can download this file from Suntec"s website. ,

[10] Firomatic Globe Type Oil Line Valves & Lever Type Fusible Link Control Valves:ISP Automation, Inc., 1035 Old Georges Road, North Brunswick, NJ 08902, Phone: 866-383-3481, FAX 866-383-3482, Email: support@ispautomation.com

[14] "The Oil Safety Valve (Service)", Charles Bursey, Sr., Fuel Oil News, February 2006 (Still trying to get the full article - October 2008 - DF) Charles W. Bursey Sr. can be reached at F.W. Webb Co. www.fwwebb.com/

[19] Thanks to reader Bernie Daraz for suggesting the need for clear photographs illustrating the OSV or oil line safety valve in the open and closed positions. Personal correspondence 2/15/2013.

Thanks to Rick Johnston for pointing out that the more likely cause of a fire safety valve in the return oil line is a burst seal on the fuel unit 4/6/2009

Thanks to reader T.R. for suggesting clarity on where oil safety valves should or should not be installed and for discussing the proper hook-up location for the Tigerloop and similar oil line prime protection & air removal devices. April 2011.

Abandon a Buried Oil Tank, How To - Abandoning Commercial Underground Tanks, Russ Brauksieck, ASHI Tech. Journal, Vol.3 No.1 Spring 1993, P. 40-41 [Reprint]

Petroleum Bulk Storage J. Sibblies, NY State DEC, Advice to Home Owners and Home Inspectors about Oil Storage Tanks - summary from ASHI Chapter Seminar.

TECHNICAL REFERENCE GUIDE to manufacturer"s model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop Weldon & Associates

As a design engineer responsible for developing and specifying boilers, dryers, furnaces, heaters, ovens and other industrial heating equipment, you face a daunting labyrinth of standards and industry regulations. Regulatory bodies sound a bit like alphabet soup, with acronyms like UL, FM, CSA, UR, AGA, ASME, ANSI, IRI, CE and NFPA tossed about. This article will help explain a common task for many thermal processing equipment specifiers: meeting the requirements of key codes — including Underwriters Laboratories (UL), Factory Mutual Insurers (FM) and the National Fire Protection Association (NFPA) — for safety valve equipment used in process heating applications.

Key to designing safety into your fuel train configurations are familiar technologies such as safety shutoff valves and vent valves as well as visual-indication mechanisms and proof-of-closure switches.

Your design skills come into play with how you take advantage of the wide range of products available. You can mix and match solenoid and safety shutoff valves — within designs from catalytic reactors to multi-zone furnaces — to create easily installed, cost-effective solutions that comply with all necessary standards. (See table.)

Make sure, however, that you start with a good grasp of valve element fundamentals. For example, examining a proof-of-closure (POC) switch underlines how reliably modern valves can ensure combustion safety. The POC unit provides an electrical contact interlocked with the controller safety circuit. In a typical design, the switch is located at the bottom of the valve, positioned to trace the stroke of the valve disc. When the disc seal reaches the fully closed position, it triggers the mechanism to push down on the contact, closing it and triggering the unit’s visual indicator to show open or closed status. As a result, the operator can act with full confidence in situations where it is critical that a safety valve be safely closed.

To provide ease of installation, many users prefer valves with modular capabilities. For example, to reduce mounting complexity, you can choose modular gas safety shut-off valves — combining a solenoid valve with an electrohydraulic motorized valve for a compact double-valve footprint, a slow-open feature and high flow rates. An accompanying actuator can provide on/off or high/low/off firing rates as well as visual indication and proof of closure for compliance with most industry standards.

Also, you may want to look for valves that include useful features such as pipe taps, which can facilitate accurate pressure readings and leakage testing.

Knowing your valve choices — and how they meet given codes and standards — can reduce the time required for design and production while facilitating compliance. This results in safer, more efficient and cost-effective heating process installations.

In order to ensure that the maximum allowable accumulation pressure of any system or apparatus protected by a safety valve is never exceeded, careful consideration of the safety valve’s position in the system has to be made. As there is such a wide range of applications, there is no absolute rule as to where the valve should be positioned and therefore, every application needs to be treated separately.

A common steam application for a safety valve is to protect process equipment supplied from a pressure reducing station. Two possible arrangements are shown in Figure 9.3.3.

The safety valve can be fitted within the pressure reducing station itself, that is, before the downstream stop valve, as in Figure 9.3.3 (a), or further downstream, nearer the apparatus as in Figure 9.3.3 (b). Fitting the safety valve before the downstream stop valve has the following advantages:

• The safety valve can be tested in-line by shutting down the downstream stop valve without the chance of downstream apparatus being over pressurised, should the safety valve fail under test.

• When setting the PRV under no-load conditions, the operation of the safety valve can be observed, as this condition is most likely to cause ‘simmer’. If this should occur, the PRV pressure can be adjusted to below the safety valve reseat pressure.

Indeed, a separate safety valve may have to be fitted on the inlet to each downstream piece of apparatus, when the PRV supplies several such pieces of apparatus.

• If supplying one piece of apparatus, which has a MAWP pressure less than the PRV supply pressure, the apparatus must be fitted with a safety valve, preferably close-coupled to its steam inlet connection.

• If a PRV is supplying more than one apparatus and the MAWP of any item is less than the PRV supply pressure, either the PRV station must be fitted with a safety valve set at the lowest possible MAWP of the connected apparatus, or each item of affected apparatus must be fitted with a safety valve.

• The safety valve must be located so that the pressure cannot accumulate in the apparatus viaanother route, for example, from a separate steam line or a bypass line.

It could be argued that every installation deserves special consideration when it comes to safety, but the following applications and situations are a little unusual and worth considering:

• Fire - Any pressure vessel should be protected from overpressure in the event of fire. Although a safety valve mounted for operational protection may also offer protection under fire conditions,such cases require special consideration, which is beyond the scope of this text.

• Exothermic applications - These must be fitted with a safety valve close-coupled to the apparatus steam inlet or the body direct. No alternative applies.

• Safety valves used as warning devices - Sometimes, safety valves are fitted to systems as warning devices. They are not required to relieve fault loads but to warn of pressures increasing above normal working pressures for operational reasons only. In these instances, safety valves are set at the warning pressure and only need to be of minimum size. If there is any danger of systems fitted with such a safety valve exceeding their maximum allowable working pressure, they must be protected by additional safety valves in the usual way.

In order to illustrate the importance of the positioning of a safety valve, consider an automatic pump trap (see Block 14) used to remove condensate from a heating vessel. The automatic pump trap (APT), incorporates a mechanical type pump, which uses the motive force of steam to pump the condensate through the return system. The position of the safety valve will depend on the MAWP of the APT and its required motive inlet pressure.

This arrangement is suitable if the pump-trap motive pressure is less than 1.6 bar g (safety valve set pressure of 2 bar g less 0.3 bar blowdown and a 0.1 bar shut-off margin). Since the MAWP of both the APT and the vessel are greater than the safety valve set pressure, a single safety valve would provide suitable protection for the system.

Here, two separate PRV stations are used each with its own safety valve. If the APT internals failed and steam at 4 bar g passed through the APT and into the vessel, safety valve ‘A’ would relieve this pressure and protect the vessel. Safety valve ‘B’ would not lift as the pressure in the APT is still acceptable and below its set pressure.

It should be noted that safety valve ‘A’ is positioned on the downstream side of the temperature control valve; this is done for both safety and operational reasons:

Operation - There is less chance of safety valve ‘A’ simmering during operation in this position,as the pressure is typically lower after the control valve than before it.

Also, note that if the MAWP of the pump-trap were greater than the pressure upstream of PRV ‘A’, it would be permissible to omit safety valve ‘B’ from the system, but safety valve ‘A’ must be sized to take into account the total fault flow through PRV ‘B’ as well as through PRV ‘A’.

A pharmaceutical factory has twelve jacketed pans on the same production floor, all rated with the same MAWP. Where would the safety valve be positioned?

One solution would be to install a safety valve on the inlet to each pan (Figure 9.3.6). In this instance, each safety valve would have to be sized to pass the entire load, in case the PRV failed open whilst the other eleven pans were shut down.

If additional apparatus with a lower MAWP than the pans (for example, a shell and tube heat exchanger) were to be included in the system, it would be necessary to fit an additional safety valve. This safety valve would be set to an appropriate lower set pressure and sized to pass the fault flow through the temperature control valve (see Figure 9.3.8).

If you have already had reason to call us for burner service, we hope that you were pleased with our performance, because that is our goal. If you have not yet called upon our service department, we look forward to your prompt satisfaction when the time comes!

MacLellan Oil will provide the labor free of charge for all mechanical parts listed. Your payment insures that every part listed will be replaced or repaired, when defective, at no cost to you.

Oil-fired water heaters, indirect-fired water heaters, additional oil tanks and additional zones are covered for an additional charge. Rates are invoiced annually.

We will thoroughly inspect, vacuum clean, lubricate, tune and adjust your burner and boiler once a year during the life of this policy, at no cost to you!

MacLellan Oil will provide the labor free of charge for the repair or replacement, when defective, for all mechanical parts listed. Commercial equipment includes any non-residential heating equipment having a firing rate of over three (3) gallons per hour. Labor coverage is limited to equipment located within boiler room.

Additionally, labor is not covered for services performed on the following, including, but not limited to: domestic hot water equipment, automatic water feeders, zone valve bodies, improper water level, draining, filling, or bleeding of the system, underground, vaulted or over 275 gallon oil tanks, cutting and removal of oil tanks, sludge removal, transfer or booster pumps, draft inducers, electrical wiring, radiators, piping of any kind, vents, duct work, damage caused by ceiling fans, hazardous waste removal, bearing assembly replacement, and services resulting from any overdue balances owed to the company. Customer will be charged prevailing rates for all such services rendered.

Parts are not covered by this contract unless specifically listed in this plan. Examples of parts not covered, including but not limited to are: domestic hot water equipment, relief valves, air conditioning equipment, electrical wiring, bearing assemblies, inaccessible equipment, obsolete parts, petrometers, secondary pumps, chimney bases, automatic water feeders, zone valve bodies, underground vaulted or over 275 gallon oil tanks, radiator valves and piping of any kind.

This policy is available to our automatic delivery customers only and will be terminated without notice if the customer fails to purchase all fuel oil on an automatic delivery system. Obtaining fuel oil from another source, failure to maintain a credit rating consistent with this company"s credit terms, or allowing someone other than an authorized representative of this company to service this equipment will declare this policy void. Should this policy be terminated for any reason no refund shall be made.

This policy covers normal usage of your oil heating equipment. Buyer and owner agree to hold this company free and harmless from all claims resulting in loss or damage to real estate or personal property, caused by oil leakage, fire, smoke, flood, freezing, power surges, power failures, premises left unattended, or any other cause whatsoever.

Safety is of the utmost importance when dealing with pressure relief valves. The valve is designed to limit system pressure, and it is critical that they remain in working order to prevent an explosion. Explosions have caused far too much damage in companies over the years, and though pressurized tanks and vessels are equipped with pressure relief vales to enhance safety, they can fail and result in disaster.

That’s also why knowing the correct way to test the valves is important. Ongoing maintenance and periodic testing of pressurized tanks and vessels and their pressure relief valves keeps them in working order and keep employees and their work environments safe. Pressure relief valves must be in good condition in order to automatically lower tank and vessel pressure; working valves open slowly when the pressure gets high enough to exceed the pressure threshold and then closes slowly until the unit reaches the low, safe threshold. To ensure the pressure relief valve is in good working condition, employees must follow best practices for testing them including:

If you consider testing pressure relief valves a maintenance task, you’ll be more likely to carry out regular testing and ensure the safety of your organization and the longevity of your

It’s important to note, however, that the American Society of Mechanical Engineers (ASME) and National Board Inspection Code (NBIC), as well as state and local jurisdictions, may set requirements for testing frequency. Companies are responsible for checking with these organizations to become familiar with the testing requirements. Consider the following NBIC recommendations on the frequency for testing relief valves:

High-pressure steam boilers greater than 15 psi and less than 400 psi – perform manual check every six months and pressure test annually to verify nameplate set pressure

High-pressure steam boilers 400 psi and greater – pressure test to verify nameplate set pressure every three years or as determined by operating experience as verified by testing history

High-temperature hot water boilers (greater than 160 psi and/or 250 degrees Fahrenheit) – pressure test annually to verify nameplate set pressure. For safety reasons, removal and testing on a test bench is recommended

When testing the pressure relief valve, raise and lower the test lever several times. The lever will come away from the brass stem and allow hot water to come out of the end of the drainpipe. The water should flow through the pipe, and then you should turn down the pressure to stop the leak, replace the lever, and then increase the pressure.

One of the most common problems you can address with regular testing is the buildup of mineral salt, rust, and corrosion. When buildup occurs, the valve will become non-operational; the result can be an explosion. Regular testing helps you discover these issues sooner so you can combat them and keep your boiler and valve functioning properly. If no water flows through the pipe, or if there is a trickle instead of a rush of water, look for debris that is preventing the valve from seating properly. You may be able to operate the test lever a few times to correct the issue. You will need to replace the valve if this test fails.

When testing relief valves, keep in mind that they have two basic functions. First, they will pop off when the pressure exceeds its safety threshold. The valve will pop off and open to exhaust the excess pressure until the tank’s pressure decreases to reach the set minimum pressure. After this blowdown process occurs, the valve should reset and automatically close. One important testing safety measure is to use a pressure indicator with a full-scale range higher than the pop-off pressure.

Thus, you need to be aware of the pop-off pressure point of whatever tank or vessel you test. You always should remain within the pressure limits of the test stand and ensure the test stand is assembled properly and proof pressure tested. Then, take steps to ensure the escaping pressure from the valve is directed away from the operator and that everyone involved in the test uses safety shields and wears safety eye protection.

After discharge – Because pressure relief valves are designed to open automatically to relieve pressure in your system and then close, they may be able to open and close multiple times during normal operation and testing. However, when a valve opens, debris may get into the valve seat and prevent the valve from closing properly. After discharge, check the valve for leakage. If the leakage exceeds the original settings, you need to repair the valve.

According to local jurisdictional requirements – Regulations are in place for various locations and industries that stipulate how long valves may operate before needing to be repair or replaced. State inspectors may require valves to be disassembled, inspected, repaired, and tested every five years, for instance. If you have smaller valves and applications, you can test the valve by lifting the test lever. However, you should do this approximately once a year. It’s important to note that ASME UG136A Section 3 requires valves to have a minimum of 75% operating pressure versus the set pressure of the valve for hand lifting to be performed for these types of tests.

Depending on their service and application– The service and application of a valve affect its lifespan. Valves used for clean service like steam typically last at least 20 years if they are not operated too close to the set point and are part of a preventive maintenance program. Conversely, valves used for services such as acid service, those that are operated too close to the set point, and those exposed to dirt or debris need to be replaced more often.

Pressure relief valves serve a critical role in protecting organizations and employees from explosions. Knowing how and when to test and repair or replace them is essential.