Water Pressure Booster Pump Installation
The typical installation consists of a booster pump and back up water tank.
The installation should not take more than a day to complete with very little disruption to the client. The pump and water tank need to as close together as possible and a power supply will have to be installed at the chosen site for the pump and tank.
The tank and pump are connected into the main water supply to the property. The water supply is routed into the tank thereafter it goes to the pump and back into the water supply and boosts your pressure in the house or office. The water is constantly going through the tank so there is no chance of stagnant water.
A supply tank is necessary for the installation for it to work effectively. If you have a pressure problem then there is not sufficient water coming into the system, therefore you cannot boost the system without a backup water supply. A booster pump needs water for it to work effectively therefore if there is not sufficient water coming in the pump will run dry and cannot run at its full potential.
The size of the tank will be determined by one of our qualified technical staff as each installation differs depending on the individual needs.
With a backup water tank you will never be without water again when the municipality are busy with emergency repairs and maintenance that can sometimes take days.
INSTALLATION GUIDE FOR ALL BOOSTER PUMPS
Pump & Supply Tank
All Booster Pumps must get there supply from water from a Storage Tank. Booster Pumps cannot simply be put in line with the municipal feed. Please refer to Schematic Drawing of Pump and Tank.
Poor piping design and installation is a common cause of poor centrifugal-pump performance or failure. Poor piping can result in:
- Performance dropout
- Impeller failure
- Bearing and mechanical seal failures
- Cracked casings
Suction piping is more important than discharge piping.
Suction Pipe size and elimination of air pockets
Piping should be at least one nominal pipe size larger than the pump suction Inlet. Velocities should be less than 2 to 3 ft/sec, and the head loss as a result of friction should be less than 1 ft per 100 ft of equivalent piping length. Suction lines should be short and free of all unnecessary turns. For flooded suctions, piping should be continuously sloping downward to the pump suction so that any vapour pockets can migrate back to the source vessel.
For static lifts, the piping should be continuously sloping upward with no air pockets (install gate valves in horizontal position). If a gate valve is to be install between Pump and Tank it is recommended the pipe size and gate valve be increased to 1 ½ times of the intake of the pump. No non-return valves, strainers or filters are to be fitted between Pump and Tank. The pump already has a non-return valve fitted to it and cannot push back on the Tank. Strainers must be fitted on the pipe work that enters the Tank. Filters can be fitted before entering Tank or on the outlet side of the pump. Make sure that filters can handle the pressure of the pump.
Upstream elbow considerations
When making upstream orientation changes, only long-radius elbows should be used. They should not be connected directly to the pump suction flange, and a minimum of at least two to five pipe diameters of straight pipe should be between the suction flange and the elbow and between successive elbows.
This reduces swirl and turbulence before the fluid reaches the pump. Otherwise, separation of the leading edges may occur, with consequent noisy operation and cavitation damage. The outlet pipe may be reduced to suit the application. Important to remember the smaller the outlet pipe the less volume of water can be pushed.
Cover the Pump
The Pump must be covered and protected from the elements. Pumps incorrectly installed are not covered under the Manufactures Warranty.
Electrical Connections to the Pump are to be done by a qualified person.
Understanding Suction Cavitation
Suction cavitation occurs when the pump suction is under a low-pressure/high-vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump, where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure.
This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition can have large chunks of material removed from its face or very small bits of material removed, causing the impeller to look spongelike. Both cases will cause premature failure of the pump, often due to bearing failure.
Suction cavitation is often identified by a sound like gravel or marbles in the pump casing.
In automotive applications, a clogged filter in a hydraulic system (power steering, power brakes) can cause suction cavitation making a noise that rises and falls in synch with engine RPM. It is fairly often a high pitched whine, like set of nylon gears not quite meshing correctly.
Discharge cavitation Discharge cavitation occurs when the pump discharge pressure is extremely high, normally occurring in a pump that is running at less than 10% of its best efficiency point. The high discharge pressure causes the majority of the fluid to circulate inside the pump instead of being allowed to flow out the discharge.
As the liquid flows around the impeller, it must pass through the small clearance between the impeller and the pump housing at extremely high velocity. This velocity causes a vacuum to develop at the housing wall (similar to what occurs in a venturi), which turns the liquid into a vapor. A pump that has been operating under these conditions shows premature wear of the impeller vane tips and the pump housing.
In addition, due to the high pressure conditions, premature failure of the pump's mechanical seal and bearings can be expected. Under extreme conditions, this can break the impeller shaft.
Discharge cavitation in joint fluid is thought to cause the popping sound produced by bone joint cracking, for example by deliberately cracking one's knuckles.
Since all pumps require well-developed inlet flow to meet their potential, a pump may not perform or be as reliable as expected due to a faulty suction piping layout such as a close-coupled elbow on the inlet flange. When poorly developed flow enters the pump impeller, it strikes the vanes and is unable to follow the impeller passage.
The liquid then separates from the vanes causing mechanical problems due to cavitation, vibration and performance problems due to turbulence and poor filling of the impeller. This results in premature seal, bearing , impeller failure and possible pump casing cracking, high maintenance costs, high power consumption, and less-than-specified head and/or flow.
To have a well-developed flow pattern, pump manufacturer's manuals recommend about 10 diameters of straight pipe run upstream of the pump inlet flange. Unfortunately, piping designers and plant personnel must contend with space and equipment layout constraints and usually cannot comply with this recommendation. Instead, it is common to use an elbow close-coupled to the pump suction which creates a poorly developed flow pattern at the pump suction.
With a double-suction pump tied to a close-coupled elbow, flow distribution to the impeller is poor and causes reliability and performance shortfalls. The elbow divides the flow unevenly with more channeled to the outside of the elbow. Consequently, one side of the double-suction impeller receives more flow at a higher velocity and pressure while the starved side receives a highly turbulent and potentially damaging flow.
This degrades overall pump performance (delivered head, flow and power consumption) and causes axial imbalance which shortens seal, bearing and impeller life. To overcome cavitation: Increase suction pressure if possible. Decrease liquid temperature if possible. Throttle back on the discharge valve to decrease flow-rate. Vent gases off the pump casing.
Cavitation can occur in control valves. If the actual pressure drop across the valve as defined by the upstream and downstream pressures in the system is greater than the sizing calculations allow, pressure drop flashing or cavitation may occur. The change from a liquid state to a vapour state results from the increase in fluid velocity at or just downstream of the greatest flow restriction which is normally the valve port. To maintain a steady flow of liquid through a valve the velocity must be greatest at the vena contracta or the point where the cross sectional area is the smallest.
This increase in velocity is accompanied by a substantial decrease in the fluid pressure which is partially recovered downstream as the area increases and velocity decreases. This pressure recovery is never completely to the level of the upstream pressure. If the pressure at the vena contracta drops below the vapor pressure of the fluid bubbles will form in the flow stream. If the pressure recovers after the valve to a pressure that is once again above the vapor pressure, then the vapor bubbles will collapse and cavitation will occur.
Causes of Pump Cavitation
- Drop in pressure at the suction nozzle due to low NPSHa
If the fluid at pump suction is not available sufficiently above the vapor pressure of liquid at operating conditions, then vaporization of liquid and formation of gas bubbles is very likely, leading to cavitation.
- Increase of the temperature of the pumped liquid
Increase in liquid temperature at the pump suction point increases the vapor pressure of the liquid. Thus it becomes more likely for operating pressure to fall below this vapour pressure limit, hence leading to bubbles and cavitation.
- Increase in the fluid velocity at pump suction
Increase in fluid velocity at pump suction can typically be caused by higher liquid flow rates than the design case. As per Bernoulli's principle, higher liquid velocity means higher velocity and lower pressure head. Frictional pressure drop in the pump suction also rises with rise in the flow rate, making low pressure and cavitation at pump suction more likely to occur.
- Reduction of the flow at pump suction
Certain minimum flow is required by the centrifugal pumps to keep them from running dry, as indicated by the pump performance curves. If liquid flow falls below this limit, possibility of developing vapour in pumps and cavitation increases.
- Undesirable flow conditions caused by obstructions or sharp elbows in the suction piping
Sharp elbows, valves, other fittings and obstructions cause more frictional pressure loss in the pump suction, thus increasing possibility of low pump suction pressure leading to cavitation.