surge dampener mud pump quotation

A well-placed suction stabilizer can also prevent pump chatter. Pump chatter occurs when energy is exchanged between the quick opening and closing of the reciprocating pump’s valves and the hammer effect from the centrifugal pump. Pump isolation with suction stabilizers is achieved when the charge pumps are isolated from reciprocating pumps and vice versa. The results are a smooth flow of pumped media devoid of agitating energies present in the pumped fluid.

Suction stabilizer units can mitigate most of the challenges related to pulsations or pressure surges, even in the most complex piping conditions. The resulting benefits prevent expensive unplanned downtime and decrease costs and inconvenience associated with system replacements and repairs.

TSC offers a broad range of drilling and production spherical pulsation dampeners. Volumetric size ranges from 10 gallon to 20 gallon capacities and pressure ranges from 3000 psi to 7500 psi. The body of the TSC spherical pulsation dampeners is manufactured from a one piece steel forging, thereby eliminating the possibility of weld fatigue failure.

The start and stop action of positive displacement pumps rapidly accelerates and decelerates fluid in motion resulting in pulsations observed as pressure spikes. Pulsation dampeners absorb the energy of these pressure spikes by accumulating and then releasing process fluid when the pump is on its suction stroke. By keeping the fluid in motion, dampeners eliminate vibration and the pulsing, inconsistent flow caused by pulsation.

Water hammer (or hydraulic shock) occurs when fluid in motion is suddenly started, stopped or forced to change direction. Quick closing valves, rapid pump startup/shutdown, even changes in the pipe profile, can cause an abrupt change in fluid velocity producing violent and sometimes catastrophic water hammer. Surge suppressors act as shock absorbers by accumulating and releasing process fluid as needed to slow the rate of fluid velocity change to a level low enough to prevent water hammer.

Our custom-designed systems will absorb excess energy pulsing through the pump and piping system by creating a low-pressure area to dampen the excess shocks and vibrations. Because a pulsation dampener regulates the release of energy, your system will be better protected and run more smoothly. After installing a pulsation dampener, customers notice that their system:

The installation of properly sized pulsation dampeners minimize vessel costs while protecting the pump and piping system and improving process efficiency and accuracy.

A pulsation dampener reduces or eliminates the variations in pressure and flow produced by reciprocating pumps. In many applications, low frequency pressure waves cause problems within a given piping system and/or process. Eccentric, cam-driven pumps are probably the most commonly applied for services that require pulsation dampening, e.g., metering pumps and reciprocating (power) pumps.

Pulsation dampeners are found in a variety of designs, but for our purposes we will focus on only gas-charged pulsation dampeners, which rely on a calculated volume of compressed gas, usually Nitrogen, which is alternately compressed and expanded in synchronization with the pump plunger to reduce or eliminate pressure pulsations. This gas volume is normally separated from the process fluid by a flexible membrane. Common membrane designs include elastomeric bladders, PTFE diaphragms, PTFE bellows or stainless steel bellows.

Pressure waves or pulses are a consequence of the alternating acceleration and deceleration of fluid velocity corresponding to the travel of the piston or plunger. The pattern and amplitude of these pulses varies with pump configuration, specifically the number and size of pistons, as well as fluid compressibility factors.

It is precisely the fluid volume above mean on the discharge cycle of each stroke, which induces these pressure pulsations into a piping system. The number of pistons offered by the pump-given that all are of identical diameter and equally phased-displace a known peak volume above mean. These constants may be influenced by fluid compressibility, but for the purpose of this explanation we’ll assume none at this point. A pulsation dampener absorbs only that portion of piston displacement above mean flow, and then stores it momentarily before discharging it during the portion of the cycle below mean flow (on the suction stroke).

A simplex pump displaces a volume of fluid above mean that is equal to about 60 percent of total displacement. A duplex pump displaces a lower fluid volume above mean, approximately half that of a simplex pump. Pumps of three or more pistons of equal diameter, stroke length and proportionally phased will always present a very small fluid volume above mean to the piping system. A triplex pump, for example, produces about a 4 percent peak, as long as fluid compressibility factors and pump efficiencies are not at issue.

These smaller fluid volumes are accounted for by the crank angle of each of the cylinders. Triplex pumps are offset by 120-deg. Quadruplex pumps are set apart at 90-deg offsets; quintuplex pumps are offset 72-deg, and so on. It is the resulting overlap in pulses that yield the smaller fluid volumes above mean.

Fluid velocity gradients follow the same mechanical velocity gradients of the eccentric cam that drives the piston(s). Halfway through the piston’s forward travel (discharge stroke), fluid velocity between the discharge check valve and the pulsation dampener begins to decay. The corresponding drop in pressure causes the membrane inside the dampener to expand since the internal gas pre-charge pressure is now higher than the line pressure. The (stored) fluid now being displaced by the pulsation dampener maintains velocity downstream of the dampener thereby reducing, if not eliminating, any downstream pulsations.

Note: A pulsation dampener removes pulses only from the line downstream of the dampener-not upstream. That’s why it’s always recommended that discharge dampeners be installed as close to pump discharge nozzles as possible. In an application of a dampener for suction stabilization (reduction of acceleration head losses), it is the velocity gradient between the supply vessel and the suction nozzle that is minimized.

Let’s begin by defining the pump details required to properly size a pulsation dampener. We will use these values in a sample calculation to help clarify the process.

The result of the previous calculation is then divided by a constant. As noted previously, the constant is a function of pump configuration. We use a conservative 1.5 for simplex pumps, 2 for duplex pumps, and 7 for triplex pumps. Remember-if the fluid is compressible, then the constant may have to be adjusted downward.

Fluid volumes above mean are well within the range of these constants. The fluid pulse above mean flow from a simplex pump, for example, is about 60 percent. When we divide full stroke displacement by 1.5 the result is a conservative 67 percent. The divisor 7 that we use for triplex pumps allows for a nominal 14 percent fluid volume above mean. While 14 percent is far above the actual 4 percent produced by triplex pumps, the higher volume is an allowance for practical reasons, specifically size and nozzle limits. Otherwise, the result would be a very small dampener relative to pump size.

Ranges of (process) temperature and pressure must be considered in any sizing calculations for pulsation dampeners. Compensations must be made for temperature variations, which affect gas density, and dynamic variations in system pressure, since sizing is based on a set pre-charge pressure.

The objective is to select a dampener that is adequately sized to handle a range of operating pressures with a single pre-charge pressure. Remember that the gas pre-charge pressure should always be based on the minimum operating pressure as the pulsation dampener will have no effect when the system pressure is below the pre-charge pressure.

Changes in ambient temperature can also influence gas density, but they’re generally disregarded for the purposes of pulsation dampener sizing. It is usually sufficient to make seasonal adjustments to pre-charge pressures, if necessary. Temperature and pressure calculations are recommended to be done using absolute values (Kelvin for temperature and BarA or PSIA for pressure).

Some fluids are highly compressible, such as cryogenics, olefins, liquefied gases, anhydrous ammonia, etc. In these instances, the benefit of lower pulsations from multiple piston pumps may be somewhat compromised. Fluid compression occurs during the leading edge of the (eccentric) crank angle. Given sufficient pressure and a high enough compressibility factor, there may be little or no overlap of pulses at all-in which case, adjustments have to be made and pulsation dampeners with larger gas volumes should be selected.

By installing a properly-sized pulsation dampener, users can reduce or eliminate pipe shake, vibration and noise. The result is a continuous flow of product which is required in many metering, mixing and spraying applications. Reduced pressure pulsations minimize long-term damage to instrumentation and pump components while improving the accuracy of many flowmeters and increasing pump efficiency.