R M Borehole Hand Pump Blog Diary 

24 November 2022

The long exhaustive testing phase is complete. The first production models are being built. A marketing campaign will commence within the next 6 months. Initially units are being made to order. 

I invite contact with potential customers who can outline their specific needs. I am prepared to discus sending on a freight-only cost basis a trail unit to humanitarian or Governmental organizations who potentially need large numbers. Please contact me at   michael.carter@xtra.co.nz  Ph +64 7 419 477   

31 08 2020

Testing continues with encouraging results. We now move into the last phase: increasing pressure. The current equivalent lift is 15 m. This will continue for 600 hrs after which the pressure will be increased to the maximum recommended lift height of 20 m. The final testing will be at equivalent of 30 m ( 30% above the recommended maximum lift height ).  

30 03 2020 

Bit by bit we inch towards the final product. As mentioned prior we wanted to reduce plunger bypass at higher pressures. Over 3 weeks we experimented with the novel idea of machining cup seals into the plunger piston which is the heart of the pump. Through this approach we are able to incorporate a double-seal configuration. 

The piston material  consists of a modern high-tech plastic with specific properties. Where the RM hand pump differs from others is that there is no mechanical force imposed during the down stroke. This action relies on gravity alone. Therefore, there should be little friction between the piston and the cylinder. Heavy duty conventional cups seals have too much friction. Moreover, it is the cup seal that commonly fails in existing pumps.

The new design of piston is now in the test rig pumping at 1 stroke/second 24-7. So far results are encouraging. It will stay in the rig for 6000 hrs. We have set 6000 hrs as the duration for which we will provide a warranty covering failure of materials.

                                                                   Cross-section of the improved pump piston 

03 12 2019

"50% of the cost and time is in the last 10% of product development". We are in the midst of this phase now. We are committed to launching a product of exceptional performance. Our product is working well. It is now down to tweaking.

Observations @ 2500 hrs operation

Volume output: Good. No significant reduction

Wear:

Webbing and guides: Very low

Plunger: Low

Cylinder: Low

Valve shafts: Moderate

Plan of action: A second test unit (TM 2) is being constructed which will be run in conjunction with the first test model (TM1). TM2 will have a stainless steel cylinder and alternative valves. One of these valves will have a in-house modification to establish if the valve shaft wear can be reduced. We are also testing an alternative plunger piston material. This material is more elastic and may result in better sealing at maximum lift heights.

18 May 2019

The latest test model is halfway through its minimum test period of 6 months of continuous running at 1 stroke/second. Throughout the last 3 months 7.5 million strokes pumped 1.95 million litres of water. There has been no failures or adjustments required. Output is the same as at the beginning of the trial.

To date pressure demand has been set at a lift head-equivalent of 15 m. Over the next 6 weeks this will be increased to a 20 m head-equivalent pressure. The last 6 weeks will be run using a 30 m head-equivalent pressure. At this point I envisage that 30 m will be the maximum recommended lift.

As the pump output exceeds the well production, water is recycled during testing. This means we can pump the well dry if need be. Interestingly once the foot valve is clear of water the pump continues to pump air. Over coming days I will measure what air pressure it can maintain as this is a sure indication that the valves and plunger are still sealing well after 3 months continuous work.

Could it be that we have designed something that can last up to 10 years in the field without maintenance? Time will tell.

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