Pump controls pressure switch

[adobejoe]

Instead of using a float switch requiring 700 ft of wire, I want a pressure actuated switch to connect/disconnect the PV panel at the pump. The Pumptrol type differential switches might work, but I want a narrow lower and upper limit, like 20 psi upper, and 18 psi lower. Any ideas?Adobe Joe

[David HK]

Hello,

I have a brand new still in the box water pressure switch which I do not require.

The technical specs are in this PDF file

http://cn.siemens.com/cms/cn/English/SBT/downloading/HVAC_Product_Home/Pressure_Sensor/Documents/Ser
ies%20Pressure%20Sensor/1.pdf

I live in Hong Kong.

If its what you want I can send it airmail on the basis of a Christmas present for somone else in the world. People in this forum do help each other.

David HK

[David HK]

For clarity this switch measuring range is from 0 to 10 bar; Output signal DC 0 to 10V; operating voltage 24v AC(?) re-check the spec for operating voltage.

David HK

[Simen]

A cheap alternative might be a pressure switch found in washing machines. They also have (often) 2 and 3 separate levels, all adjustable on and off pressures. Though they are meant for low pressures... (5-10psi?)

I myself are using one of these in my wooden boat as a automatic bilge-switch; connected via a thin hose to a small bellhouse (upper half of a plastic sodabottle, where the hose are fastened in the cork) in the bottom of the bilge. It has worked flawless for 2 years now.

[adobejoe]

DavidHK,

Very generous of you, but I do not think this will work. It requires 24 V AC.  All I have is 12 V DC from solar panel. What I think I need is  purely mechanical switch that opens/closes contacts. That will then control (connect) the solar PV panel to complete a circuit. My pressure range is 38 ft (18 psi) cut in or turn on and 46 ft (20 psi cout out or turn off. The washing machine switch is a good idea, but too low pressures.

Adobe Joe

[ghurd]

Maybe look some of the simple old types.

I used to have to mess with a well system that often became water logged.

It was a spring (reminds me of a cheap wall thermostat) and 2 adjusting screws.

One screw set the On pressure, other set the Off.

Been a long LONG time, but I don't see why it couldn't have been adjusted pretty tight.

G-

[Simen]

I'm just guessing the psi those washing machine pressure switches operates at; it's possible they can be adjusted much higher. Point is that you can probably get them for free at the junkyard... Wouldn't hurt test one.

Those Ghurd are talking about are very similar in function. Offhand, equipment that use them that i can think of would be heating elements for swimming pools etc.

[tanner0441]

hi

Have you thought of a standard No-Float switch, electronic level controler, rectify the AC at the pump 3 stainless probes long common, short upper level, medium lower level.

Also electronic bilge pump switches, just a block with 2 stainless strips round it with a timer so the pump continues for 10 seconds after the to strip is exposed.. 12 to 36 V again rectify at the pump.

Brian.

[adobejoe]

There is no AC at the pump, it is a 12 V DC submersible and a 12 Volt Kyocero PV panel. I htink the best is some type of diaphragm type mechanical switch...will keep looking.Adobe joe

[alcul8r]

Digi-key is not cooperating with my dial-up right now, but I'll bet you could find a pressure transducer in the right range with either 20 ma or 0-5v output, use a comparator against a 10-turn pot and be all set.

[cyplesma]

for an AC switch use a small 100 watt inverter.

[cyplesma]

better yet check this site:

http://www.inspect-ny.com/water/WaterPumpAdjust.htm