Flexible pipe for well pumps [RE-wrenches]

[Windy Dankoff, Dankoff Solar]

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Change of subject from:  Need a Deep Well Pump Solution [RE-wrenches]

Brad Bassett's message:
>...
>
>In general I do not recommend using flexible hose for well pumps. They
>are generally made with vinyl or rubber, both of which can leach various
>hydrocarbons into the water, and so are rarely rated for potable water
>(Even if vinyl hose is rated, do you trust the raters on this issue,
>also I consider it an environmentally undesireable material). Also, it's
>sometimes hard to find hose rated for the pressures you're talking about
>at that depth.
>


Brad,

You are right about vinyl (soft PVC) or rubber, but that's not what
is typically used for flexible well pipe.

Polyethylene (PE) pipe (black flex) that is rated for drinking water
is considered to be very free of leach-out or out-gassing. It is much
more pure, and more environmentally safe in manufacture and disposal
than PVC. It's the stuff that the softer plastic food bags and milk
jugs are made of. It's also popular for potable water storage tanks.

We now have 15 years of success using 100 PSI PE pipe to depths of
230 feet to hang diaphragm-type solar submersibles. This is the
common pipe you can buy anywhere and connect with hose clamps
(doubled).

We have 6 years of success using 200 PSI PE pipe (type SDR-9 or
SIDR-7) with bronze compression fittings, to depths of 600 feet. That
particular pipe is used in many municipal water systems to run main
feeds to homes, etc. They use it because the thick wall and
compression fittings are extremely rugged underground, not because of
the pressure-rating per se.

We actually exceed the pressure rating by going 600 feet (260 PSI).
The 200 PSI official rating is for 77°F. At typical well temperature
around 55°, it is stronger. Also, it has a substantial safety factor.

On rare occasions we hear of somebody making a faulty pipe
connection, but I have never heard of a failure of properly installed
PE pipe in a well, even in spite of the pressure pulsations inherent
in diaphragm or piston solar pumps. PE is one of those rare modern
materials that is very cheap AND clean and reliable.

Quick history of well pipe conventions:

The drilled-well pump industry began in USA during the "iron age".
So, the industry began with galvanized steel pipe, and the associated
equipment to install rigid pipe. PVC wasn't accepted for well pipe
until just starting in the 60's. Threaded PVC has a thick wall, so
it's rigid too. The N. American industry favors rigid pipe because
that's what it grew up with.

In Europe and Africa, well-drilling was established more recently,
during the PE age. PE pipe is the dominant standard there. It is
either installed by hand, or by a truck with a large-diameter winch
MUCH more quickly and easily than rigid pipe.

PE pipe is popular here for solar pumps because many installers are
solar or electrical contractors, not water well contractors. They
don't have the rig to install rigid pipe.

There is another type of flexible pipe that is well accepted for
wells. It is thin, fabric-reinforced stuff that lays flat like fire
hose. One brand is "Well Master". It's awfully expensive though.

Windy

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