The Bamford "Hi-Ram Pump ®"
Questions and Answers.
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Questions and Answers.
How many sizes of Bamford Hi-Ram Pump are there?
There is one size initially, normally using a 25 mm drive pipe. While the operating principle of the pump applies to larger pumps, this version is the one with the widest usage.
What head of water is required to operate the Bamford Hi-Ram Pump?
The pump will operate with a 1 metre drive head of water. However, 1.5 metres should be regarded as the normal minimum drive head, and where possible 2 metres or more should be used. For a given flow of water to drive the pump, the higher the drive head the more water will be pumped into the delivery pipe.
The pump is set up to work best with drive heads between 2 and 6 metres, although higher drive heads can be used in some circumstances.
How high can the pump raise water?
A drive head of 2 metres of water can achieve an output head of over 100 metres, and a drive head of 1.5 metres can give over 50 metres output head. The quantity of water delivered at these maximum heads is small. Except in special circumstances, a realistic working height would be about 60% of the maximum possible height.
For drive heads over 2 metres, greater output pressures can be achieved.
How much water will the Bamford Hi-Ram Pump pump?
About 1500 litres of water a day can be lifted 20 metres from a drive head of 2 metres and an inlet flow of 20 litres a minute.
The amount pumped will be more for higher drive heads and lower output heads. The water flow rates in and out of a particular pump will also vary with the pump installation, and are further dependent on the drive pipe and the drive head.
How can the pump be adjusted for different operating conditions?
One of the two moving parts in the waste valve mechanism is a stainless steel tube that determines the flow of water through the pump. As this part is easily changed, a series of alternative tubes are used to adjust the amount of water that will go through the pump.
By this means, the pump is adjusted for best operation in each particular installation. The use of the alternative tubes also allows the pump to be "turned down", for example if the amount of water to drive the pump is reduced because of dry weather.
How important is the drive pipe in the operation of the pump.
The drive pipe is most important because its construction determines the magnitude of the "water hammer" during the operating cycle. This water hammer determines the maximum pressure that can be reached by the pump, and the amount of water that can be pumped. The pump should normally have an operating cycle time of about one second.
The Bamford Hi-Ram Pump can be used with a pre-fabricated drive pipe assembly, measuring about 1.75 metres by 0.75 metres by 0.1 metres when constructed of steel. Such a combination can be used to provide a "package pump" for "connection" to a suitable source of water.
Details for the construction of suitable drive pipes are provided with pumps offered for sale. The normal length of drive pipe shown in the instructions is around 10 metres.
When higher drive heads are used, for example 5 metres or more, the normal drive pipe may give a cycle time that is too short for the pump to run properly. If this happens it may be necessary to increase the length of the drive pipe which will increase the cycle time.
Must the drive pipe be made of steel?
Because of its rigidity, steel pipe gives the greatest water hammer effect, which provides the most efficient operation of the pump. The use of steel pipe is recommended wherever possible.
The use of high-pressure hard plastic pipe may be possible, but with significantly reduced performance. In some cases such plastic pipe may be preferable where the reduction in performance is acceptable. For example, plastic pipe may be easier to install, and may avoid problems arising from corrosive water.
Normal agricultural plastic piping should not be used for the drive pipe. While it may operate with the performance reduced even more, the water hammer is likely to burst the pipe after a period of operation.
How should the drive pipe be installed?
The drive pipe does not need to be in a single straight line, or at any particular angle to the horizontal. For convenience of transport to the location where the pump will operate, the drive pipe can be assembled from shorter lengths of pipe connected together.
However, the drive pipe should be regarded as one aspect of the pump installation, which also involves the need to collect water and bring it to the pump. More details for pump installation are given in the section "Pump Installation'
When a pipe is used to collect water to drive the pump, the entrance of the pipe is best located well below the surface of the water, in still water, away from the bottom, and with a filter. It is important to minimize the possibility of debris or air bubbles being drawn into the drive pipe.
For gently sloping ground, the distance from the source of water to give a drive head of about two metres can be much longer than the drive pipe length. In this situation, water can be brought along a feed pipe or channel to a relatively small header tank near the pump. A tank or drum of around 200 litres capacity is suitable. The drive pipe is then connected to this small tank in conjunction with a standpipe to give a suitable drive head for the pump.
As shown in the section "Pump Installation", it is recommended that a standpipe always be used at the start of the drive pipe.
What happens if bubbles of air flow into the drive pipe?
Air bubbles reduce the amount of water hammer in the drive pipe. This will reduce the efficiency of the pump, or may cause it to stop.
Can a siphon over an embankment be used to work the pump?
While a siphon over an embankment may be satisfactory, try to avoid this arrangement because of the problems of establishing and maintaining a siphon.
Air nearly always collects in the siphon over a period of weeks or perhaps days. This reduces the efficiency of the pump, and can cause it to stop unless the air is periodically flushed out.
What type of pipe should be used for the delivery pipe?
High-pressure piping, plastic or metal, is recommended for at least the first 20 metres at the pump end of the delivery pipe. Except for high lifts, agricultural grade plastic piping should be suitable for the remainder of the delivery pipe. If there is any doubt about the performance of agricultural grade plastic piping, high-pressure piping should be used for the full length.
Although the delivery flow rate is low, the minimum size recommended for the delivery pipe is pipe having an internal diameter similar to that of 25 mm (or 1 inch) metal pipe (i.e. around 22 mm or larger). This is because during pump operation there are pressure pulses that travel up and down the delivery pipe. High-pressure plastic pipe has thicker walls and a smaller inside diameter, and where used the next larger nominal size pipe should be selected (i.e. 32 mm high-pressure plastic pipe).
There is much to be said for the use of 40 mm delivery pipe which makes best use of the characteristics of the pump. In addition a 40 mm pipe is large enough for use with a powered fire fighting pump should you ever need a lot of water in a hurry.
It is normally necessary to restrain uphill sections of the delivery pipe, so that it cannot move downhill. If the delivery pipe is not restrained, the repeated pressure pulses coming from the pump will probably cause the pipe to "walk" downhill.
How do I start the Bamford Hi-Ram Pump?
Prior to starting the pump, water should be flushed through the drive pipe and the pump to ensure that no air is trapped between the source of water and the pump. Holding the waste valve mechanism open can do this. It can also help if the delivery pipe is not connected until after the drive pipe has been flushed out.
As part of the pump, there is a gate valve into which the drive pipe is connected. This gate valve can now be closed, so that the drive pipe remains full of water. The delivery pipe should be connected if this has not already been done.
The gate valve should now be opened to let water into the pump. The pump may start automatically, or the waste valve may simply close and prevent water flowing to waste. If necessary, the waste valve can be moved up and down by hand until automatic operation of the pump begins.
The pump requires a certain amount of back pressure in the delivery pipe for correct operation. This is why manual operation of the waste valve may be necessary to initially build up some pressure in the delivery pipe. If the delivery pipe is long and sloping gently uphill, it may take a while to get sufficient back pressure.
Where the delivery head is small, in some circumstances the back pressure may not be enough for correct pump operation. If necessary this can be overcome by partially restricting the water flow coming out of the delivery pipe. However, there is an alternative drive pipe which is designed for installations where the delivery head is small.
Final adjustment for best performance should then be done when the delivery pipe is full of water and at operating pressure.
Once the pump is operating normally, and the drive pipe and delivery pipe are both full of water, the pump can be stopped and started as necessary by simply turning the gate valve off and on.
What does a normal operating cycle look like?
Each operating cycle normally takes about one second, with the water flow from the top of the waste valve housing starting and stopping as the waste valve opens and closes.
The stainless steel tube inside the waste valve housing goes up and down about 40 mm during each cycle. When a pump is initially being started, the tube might cycle up and down over a much shorter distance until the full outlet pressure in the delivery pipe is reached.
Bamfords, Post Office Box 11, HALL ACT 2618, AUSTRALIA
Phone +(61 2) 6227 5532 Fax +(61 2) 6227 5995
Bamford Industries NSW BN97702171, and John Bamford and Associates NSW L8632225
"Hi-Ram Pump" is a Registered Trade Mark
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Home Page http://www.bamford.com.au