Suitability Of Pump & Pipes : Concerned Citizen From Bangalore!
Submitted by iwp on June 19, 2009 - 01:16
This is with reference to our Apartment located in Bangalore.
Our borewell is ~800 feet deep and the builder has installed a 7.5 HP motor, 20 stage pump to suit our needs.
Appreciate your advise on the following:
1. Whether 7.5 HP motor, 20 stage pump is aligned to a deivery head of 800 feet.
2. The discharge is constructed out of UPVC pipes. They appear to be quite rigid and are installed in sections of ~10 feet length (80 odd pipes). What is the currently reliability associated with UPVC pipes? Is it the latest trend? What about GI pipes from the technical and cost standpoint?
Thanks in advance for your response.
Regards,
Venu
Comments
1.
Dear Venu,
Although your bore well is 800 feet deep, this does not mean that the delivery head is 800 feet. Even if groundwater is stuck at 800 feet, it rises to some level in the bore well known as the static water level because of artesian pressure. The suction head equals to the depth at whcih the pump has been installed.
As it is difficult to make extrusions using polyvinyl chloride (PVC), it becomes necessary to add plasticizers to make the compound pliable. As plasticized PVC is dense, brittle and susceptible to cracking, unplasticized PVC (UPVC) was invented by adding certain other additives which protects it from weathering and imparts high impact strength. UPVC pipes are non-corrosive with glossy smooth finish both internally and externally. They do not support bacterial growth or encrustation. They are non-toxic with high quality. They have great strength with uniform wall thickness. They are cost effective compared to other conventional pipes such as stainless steel, brass or GI pipes.
Your description gives an idea that your entire bore well is fitted with UPVC pipes. This is not correct. Casing pipe is normally installed in bore wells against the top soil and weathered rock occurring to a depth of around 100 feet, leaving the hard rock beyond that depth blank without casing.
Best wishes,
Dr. R. Jagadiswara Rao
Retired Professor of Geology
Sri Venkateswara University
Tirupati, AP 517502
rjagadiswara@gmail.com
(Presently on a visit to USA)
Dr. R. Jagadishwara Rao Professor of Geology Retired Sri Venkateswara University Tirupati, AP 517502, India rjagadiswara@gmail.com
2.
Dear Venu,
As far as my knowledge goes the 7.5 hp 20 stage pump if a 100 diameter pump it is suitd for a maximum head of 180 m, the model is available with Suguna company.
But then the working head need not me equal to the depth of the borewell , it s calculated on the depth at which you have struck water, the pumping water and the delivery point.
As regards the UPVC pipes , i think they are suited for installation up to 400ft, it is true that people do install these pipes now a days and are replacing the normal G.I Pipes, especially because they are cheaper and lighter than the GI pipes, it does have its advantages, but without centralizers for the pump and pipes it is a risk to install any such system. Due to the vibration when the pump is in use there is a chance that the pipes may give way at the coupling. To be on the safe side, one should install a wirerope as secondary support.
Regards,
Dr. Anil Lalwani
http://www.wellwaterworks.com
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