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Looking for some technical assistance regarding the use of hydram


A water supply project in Sumba Indonesia involves the use of a hydram. The hydram that has been installed has a supply head of ~6m and is required to pump to ~26m. The supply flow is approximately 30L/min. The drive pipe is 2" and the discharge pipe is 1". When the pump was commissioned, it did not pump water to the tank at 26m. The delivery line was disconnected and a flow of 5L/min was confirmed at a height of 20m. From what I understand from the theory, it should be able to pump another 6m into the tank. It was also confirmed that there were no blockages in the line between where it was broken and the tank. Any technical assistance would be much appreciated

8 Answers


Hi Binaya,

First let me say I am no expert on hydrams although I have had some interaction with them.

Is there a possibility of getting some photos and further design details of the hydram please?

Prof Terry Thomas of the Development Technology Unit at the Uni of Warwick is the guru on hydrams and can be contacted via

In the meantime: If the theory says 26m and it achieves 20m then it sounds like a tweaking issue. Is there enough air in the chamber to provide the opportunity for the second valve to open at the higher output pressure? Is the outlet from the pressure vessel actually 1" or should it be smaller? Have they tried varying the settings on the valves? Sometimes adding a washer to the first valve changes the dynamics and thereby improves or worsens the performance. Similarly changing the gaps and rubber types has an effect.

Wishing them every success!



Hi Binaya,

There may be two reasons for your hydram not able to lift water in Fall / Lift ratio of 6/26 :

(a) Volume of driving water required to operate 2''/1'' Hydram is 75 to 150 Liter per minute(LPM); whereas in your case supply inflow is 30 LPM only .

(b) I feel most likely air is also entering your drive pipe with water or there may be some leakages in your drive pipe.

I have following suggestions to overcome your problem:

(a) You should install two 1''/ 0.5'' Hydram in parallel or in tandem instead of one 2''/1'' Hydram. Operate initially one 1''/ 0.5''Hydram and when sufficient quantity of supply inflow is available then use the second 1''/ 0.5''Hydram simultaneously.

(b) Drive pipe should be free of any leakages in their joints.

(c) Drive pipe end should be one feet below water level in the feeding tank so that only water enters the drive pipe.

If you take above mentioned remedial measures then with fall of 6 meter you will be able lift water to 26 meter easily.

With warm regards

Col Binay Kumar(Retd)

Prakriti Biotech Farm, Hazaribag, India


Hello Steve and Binay,

Thankyou very much for your feedback regarding the hydram in Sumba Indonesia and apologies for my delayed response.

Hi Binay,

With regards to the size of the hydram, I understand a 2" drive pipe / ram should be suitable for a flow of 33L/min? I've based this on information from along with a couple of other publications. Is there a particular reference for the 75 - 150L/min requirement?

With regards to the drive pipe, there were some minor leaks at the lower end which we will resolve. The drive pipe is at least 30cm below the surface of the water in the header tank so I think this should be ok. Thanks again for your help!

Hi Steve,

I've attached a photo - hopefully it's clear enough. The discharge line is 1 1/2". The air chamber could potentially be the issue as we had trouble with a couple of leaks from the welds at the top of the chamber. We also didn't have a snifter valve so I suspect the chamber was filling up with water. The other issue could be with the discharge check valve passing water back which we will try to get resolved.

image description

They were able to tweak the waste valve a bit to improve the flow. The strange thing was that it still had a more than adequate flow at 20m, but just couldn't push it another 6m. Thanks also for your help!




Check this site - also concerning ram pumps in Indonesia.


The below is from Prof Terry Thomas at Warwick University. I received it a long while ago and thought I had posted it to the site but cannot see it here so please read on:

Dear Binaya


You seem to be getting reasonable performance (efficiency of about 60%) when delivering 5 litres/min to 20m, yet you get no delivery to 26m. The absolute max delivery head (in m) for a steel pipe system is about 140 x max drive-water velocity (in m/s). At mean flow of 0.5 L/s in a 2" pipe your max velocity as the impulse valve shuts would be between 0.2 and 0.35 m/s; 0.2 m/s is only just enough to deliver to 26m and as Steve has said, minor defects could make it insufficient (defects such as slow delivery valve reclosure, flexibility in pump body or drive pipe or impulse valve, leaky impulse valve etc) - I don't know which ram pump design you have or whether your drive pipe slope is small). If your drive pipe is plastic, the max delivery head falls to about 40 x max water velocity. Can you adjust the impulse valve to increase the drive flow? (I am assuming your cycle time is not longer than 1.5 seconds), or have you hit the limit on available drive water? Your drive pipe diameter is rather large for this low drive flow.

good luck



Dear Binaya and Phil, I agree with Steve regarding driving flow of 30 Litres per minute with a fall of 6 Metres for 2''/1'' Hydram, to lift water to 26 Metres height is low. The following references are forwarded regarding drive flow required for 2''/1'' Hydram : (a) FAO Irrigation and Drainage Paper - 43; Section 4.9.3 : Water Lifting Devices : Volume of water required to operate 2''/1'' Hydram - 27 to 55 Litres per minute) (b) Development Technology Unit, Warwick University; New Development in Hydraulic Ram Pumping; Technical Release - 13, 1996 : For 50 mm Drive Pipe - 100 Litres per minute and for 25 mm Drive Pipe - 25 Litres per minute (c) Development Technology Unit, Warwick University; DTU S-2 Ram Specification; Technical Release - 14, 1998 : For 37.5 mm (1.5'') Drive Pipe - 40 to 80 Litres per minute and for 50 mm (2'') Drive Pipe - 60 to 120 Litres per minute. After seeing the photograph of you Hydram, the following remedial measures are suggested:- (a) Check the Volume of Air chamber of your 2''/1'' Hydram ? Its volume should be 3.4 gallon ( 12.85 litres). As a thumb rule, the length of Air chamber with 4'', 6''& 8'' pipe will be 62'', 40'' & 27 '' respectively. (b) For smooth operation, sniffer valve to be provided 2 cm below delivery valve and it will not cost you much. (c) Even after having required size of Air Chamber and after providing sniffer valve ; if your 2''/1'' Hydram, is not able to lift water to 26 Metres height with a fall of 6 Metres; then as I had suggested in earlier mail of 05 Oct 2014 please install two 1''/0.5'' Hydram and you will be able to lift the water upto 26 metre height. Wish you Happy pumping with hydram. With warm regards Col Binay Kumar


If the pump is pushing substantial flow at 20m,put a clear hose and hoist it up a tree. I am almost certain you will get your 6m plus though with reduced flow. Your drive head is too good to have head issues at 26m even with a crude hydram if its pumping to 20m. If it works with the hose check your delivery pipe again. I have experienced this several times and no matter how I twicked the hydram it seemed to always not do the "last mile". I have been fabricating and installing since 2000 using the DTU model and I am unable to stop myself.


The best thing is to have different sizes of ram pumps for different flow ranges for you to chose from. For 30 liters/min a 1" ram is the best. With a 6 meter fall and a delivery head of just 26 meters, you should be able to get 4.6 liters/min or 6650 liters per day on top of the hill. Have the problems been solved in the meantime? I'm working with AIDFI in the Philippines and are installing our own model ram pump. We have ten different sizes. Sometimes, with the source varying over the seasons, it is a good idea to place two pumps in parallel. This was already suggested by Col Binay Kumar.