Water hammer is normally a major concern in pumping systems and ought to be a consideration for designers for a number of reasons. If not addressed, it could possibly cause a number of points, from damaged piping and supports to cracked and ruptured piping parts. At worst, it may even cause damage to plant personnel.
What Is Water Hammer?

Water hammer occurs when there is a surge in pressure and move price of fluid in a piping system, causing fast adjustments in pressure or force. High pressures may end up in piping system failure, corresponding to leaking joints or burst pipes. Support elements can even expertise sturdy forces from surges or even sudden flow reversal. Water hammer can occur with any fluid inside any pipe, however its severity varies relying upon the circumstances of each the fluid and pipe. Usually this happens in liquids, but it can also occur with gases.
How Does Water Hammer Occur & What Are the Consequences?

Increased stress happens each time a fluid is accelerated or impeded by pump situation or when a valve position adjustments. Normally, this stress is small, and the speed of change is gradual, making water hammer virtually undetectable. Under some circumstances, many kilos of stress may be created and forces on supports can be nice sufficient to exceed their design specifications. Rapidly opening or closing a valve causes strain transients in pipelines that can lead to pressures well over regular state values, inflicting water surge that can critically injury pipes and course of management tools. The importance of controlling water hammer in pump stations is well known by utilities and pump stations.
Preventing Water Hammer

Typical water hammer triggers embody pump startup/shutdown, energy failure and sudden opening/closing of line valves. A simplified mannequin of the flowing cylindrical fluid column would resemble a steel cylinder suddenly being stopped by a concrete wall. Solving these water hammer challenges in pumping methods requires both decreasing its effects or preventing it from occurring. There are many options system designers want to keep in mind when developing a pumping system. Pressure tanks, surge chambers or related accumulators can be utilized to absorb stress surges, that are all useful instruments in the struggle towards water hammer. However, stopping the stress surges from occurring within the first place is commonly a greater strategy. This could be accomplished through the use of a multiturn variable pace actuator to regulate the pace of the valve’s closure rate at the pump’s outlet.
The development of actuators and their controls present alternatives to use them for the prevention of water hammer. Here are เพรสเชอร์เกจ where addressing water hammer was a key requirement. In all instances, a linear characteristic was important for circulate management from a high-volume pump. If this had not been achieved, a hammer impact would have resulted, doubtlessly damaging the station’s water system.
Preventing Water Hammer in Booster Pump Stations

Design Challenge

The East Cherry Creek Valley (ECCV) Southern Booster Pump Station in Colorado was fitted with high-volume pumps and used pump verify valves for flow management. To keep away from water hammer and probably critical system harm, the applying required a linear flow characteristic. The design problem was to obtain linear move from a ball valve, which typically exhibits nonlinear move characteristics as it is closed/opened.
Solution

By utilizing a variable speed actuator, valve place was set to achieve completely different stroke positions over intervals of time. With this, the ball valve could possibly be pushed closed/open at various speeds to attain a extra linear fluid move change. Additionally, within the occasion of a power failure, the actuator can now be set to close the valve and drain the system at a predetermined emergency curve.
The variable speed actuator chosen had the aptitude to control the valve position based mostly on preset occasions. The actuator might be programmed for as a lot as 10 time set factors, with corresponding valve positions. The pace of valve opening or closing might then be managed to make sure the desired set position was achieved at the correct time. This superior flexibility produces linearization of the valve traits, allowing full port valve choice and/or significantly lowered water hammer when closing the valves. The actuators’ integrated controls were programmed to create linear acceleration and deceleration of water throughout normal pump operation. Additionally, within the event of electrical energy loss, the actuators ensured rapid closure by way of backup from an uninterruptible power provide (UPS). Linear flow price

change was also offered, and this ensured minimum system transients and simple calibration/adjustment of the speed-time curve.
Due to its variable speed functionality, the variable velocity actuator met the challenges of this installation. A journey dependent, adjustable positioning time offered by the variable speed actuators generated a linear move via the ball valve. This enabled fantastic tuning of working speeds through ten totally different positions to prevent water hammer.
Water Hammer & Cavitation Protection During Valve Operation

Design Challenge

In the realm of Oura, Australia, water is pumped from multiple bore holes into a collection tank, which is then pumped right into a holding tank. Three pumps are every geared up with 12-inch butterfly valves to manage the water circulate.
To protect the valve seats from injury attributable to water cavitation or the pumps from operating dry in the event of water loss, the butterfly valves must be capable of fast closure. Such operation creates large hydraulic forces, often known as water hammer. These forces are sufficient to trigger pipework harm and should be prevented.
Solution

Fitting the valves with part-turn, variable velocity actuators permits totally different closure speeds to be set during valve operation. When closing from totally open to 30% open, a fast closure fee is set. To avoid water hammer, during the 30% to 5% open part, the actuator slows all the method down to an eighth of its previous pace. Finally, through the last

5% to finish closure, the actuator speeds up again to reduce cavitation and consequent valve seat injury. Total valve operation time from open to close is around three and a half minutes.
The variable pace actuator chosen had the potential to vary output speed primarily based on its place of travel. This superior flexibility produced linearization of valve traits, allowing simpler valve selection and decreasing water

hammer. The valve pace is defined by a maximum of 10 interpolation points which could be exactly set in increments of 1% of the open position. Speeds can then be set for up to seven values (n1-n7) primarily based on the actuator type.
Variable Speed Actuation: Process Control & Pump Protection

Design Challenge

In Mid Cheshire, United Kingdom, a chemical firm used several hundred brine wells, each utilizing pumps to switch brine from the well to saturator units. ไดอะแฟรม ซีล is controlled using pump delivery recycle butterfly valves pushed by actuators.
Under normal operation, when a decreased circulate is detected, the actuator which controls the valve is opened over a period of eighty seconds. However, if a reverse move is detected, then the valve must be closed in 10 seconds to protect the pump. Different actuation speeds are required for opening, closing and emergency closure to ensure safety of the pump.
Solution

The variable speed actuator is prepared to present as a lot as seven totally different opening/closing speeds. These can be programmed independently for open, shut, emergency open and emergency close.
Mitigate Effects of Water Hammer

Improving valve modulation is one answer to contemplate when addressing water hammer concerns in a pumping system. Variable pace actuators and controls present pump system designers the pliability to continuously control the valve’s working velocity and accuracy of reaching setpoints, another activity aside from closed-loop management.
Additionally, emergency secure shutdown may be supplied using variable speed actuation. With the capability of continuing operation utilizing a pump station emergency generator, the actuation technology can offer a failsafe choice.
In other phrases, if an influence failure happens, the actuator will close in emergency mode in numerous speeds utilizing energy from a UPS system, allowing for the system to empty. The positioning time curves may be programmed individually for close/open course and for emergency mode.
Variable velocity, multiturn actuators are additionally an answer for open-close obligation conditions. This design can present a gentle begin from the start place and soft cease upon reaching the top position. This degree of control avoids mechanical strain surges (i.e., water hammer) that can contribute to premature part degradation. The variable pace actuator’s capacity to provide this control positively impacts upkeep intervals and extends the lifetime of system elements.
Share