Fuel pump as a RO booster pump

I have noticed relatively cheap fuel pumps on eBay...
So recently new BOSCH pump for $50 which can deliver 80PSI.
I was thinking if such pump could be used for boosting
tap water pressure before RO/DI filter...

My tap water pressure is only 40PSI but the filter
likes it to be 60-80PSI and the filter eficiency goes
down very much, especially in winter, when water is cold.

Anybody knows how does this pump work ?
Wouid it be sufficient ? Too strong ? Too weak ?

Pszemol wrote:
I have noticed relatively cheap fuel pumps on eBay...
So recently new BOSCH pump for $50 which can deliver 80PSI.
I was thinking if such pump could be used for boosting
tap water pressure before RO/DI filter...

I bought my pump on ebay for $80. It included a solenoid and pressure
switch to turn the pump off when the back pressure hits 40psi. I think
you'd need these to turn the pump on and off when needed.

I've also heard that fuel pumps use the fuel as a lubricant/coolant.
I'd venture a guess that they wouldn't stand up to water due to corrosion.

--Kurt

"Pszemol" wrote in message
...
I have noticed relatively cheap fuel pumps on eBay...
So recently new BOSCH pump for $50 which can deliver 80PSI.
I was thinking if such pump could be used for boosting
tap water pressure before RO/DI filter...

My tap water pressure is only 40PSI but the filter
likes it to be 60-80PSI and the filter eficiency goes
down very much, especially in winter, when water is cold.

Anybody knows how does this pump work ? Wouid it be sufficient ? Too
strong ? Too weak ?

I once read an article on just such an idea.

I the article the authors obtained a pump from a well known RO Filter
supplier and a pump from a Diesel Lorry.

Both pumps looked identical and both ran on 24volts DC

They then proceeded to strip both pumps and compare the internal workings.

At the end they concluded that both pumps were identical.

The only problem was the here in the UK RO Pumps are cheaper than Lorry
pumps.

If I can find the article I will post a link.




--
Posted via a free Usenet account from http://www.teranews.com

"KurtG" wrote in message ...
Pszemol wrote:
I have noticed relatively cheap fuel pumps on eBay...
So recently new BOSCH pump for $50 which can deliver 80PSI.
I was thinking if such pump could be used for boosting
tap water pressure before RO/DI filter...

I bought my pump on ebay for $80. It included a solenoid and pressure
switch to turn the pump off when the back pressure hits 40psi. I think
you'd need these to turn the pump on and off when needed.

I tried one pump of this kind but it was constantly cycling
between on/off states so is was very noisy driving me nuts :-)
The switch aparently was turning the pump on for about 1/4 second,
then the pressure build up turned of the switch and after about
another 1/2 second the pressure was down (water was "consumed"
by the RO filter) and the cycle repeated over and over again...

What pump have you got ? Manufacturer ? Model number ?
What RO system do you use it with ? Is RO filter 60gph or 100gph?

I've also heard that fuel pumps use the fuel as a lubricant/coolant.
I'd venture a guess that they wouldn't stand up to water due to corrosion.

You are probably correct. I did not think of corrosion :-)

Pszemol wrote:
What pump have you got ? Manufacturer ? Model number ?
What RO system do you use it with ? Is RO filter 60gph or 100gph?


http://cgi.ebay.com/ws/eBayISAPI.dll...0935&rd=1&rd=1

Mine is a 100 gallon/day and I bought a 4 gallon pressure tank so it
wouldn't cycle on/off (that and I can run a line to my kitchen sink for
drinkable water).

--Kurt

"KurtG" wrote in message news:4vtwh.3953$ch1.684@bigfe9...
Pszemol wrote:
What pump have you got ? Manufacturer ? Model number ?
What RO system do you use it with ? Is RO filter 60gph or 100gph?


http://cgi.ebay.com/ws/eBayISAPI.dll...0935&rd=1&rd=1

Mine is a 100 gallon/day and I bought a 4 gallon pressure tank so it
wouldn't cycle on/off (that and I can run a line to my kitchen sink for
drinkable water).

And this pressure tank is before the filter, I presume ?

Pszemol wrote:
And this pressure tank is before the filter, I presume ?

After. It also works as a reservoir (4 gallons) for finished water.

I've been looking for a check valve, so I can have drinking water even
while it's busy making water for a larger storage tank.

Of course, I need to get off my backside and install this thing. It's
been sitting my closet for two weeks already.

--Kurt

"KurtG" wrote in message .. .
Pszemol wrote:
And this pressure tank is before the filter, I presume ?

After. It also works as a reservoir (4 gallons) for finished water.

So how would it prevent pump cycling on/off ?

I've been looking for a check valve, so I can have drinking water even
while it's busy making water for a larger storage tank.

Of course, I need to get off my backside and install this thing. It's
been sitting my closet for two weeks already.

I see... so you did not realize yet that it will not work this way :-)
The pump cycles because there is very limited volume of
water befween the pump and the membrane and the lines
do not expand a lot to regulate pressure...
To prevent pump from cycling in a very anoying way you
rather connect small pressure tank BEFORE the filter.
Exactly between the pump and the filter. You pump the tank
to the high pressure and the pump is pumping water against
the pressure tank bladder. When pressure reaches high point
pumping stops and the energy is acumulated in the compressed
air in the tank bladder. Thanks to the pressure tank it takes
longer time for the pump to go between off/on/off states and
the noice is less anoying :-)

Pszemol wrote:

So how would it prevent pump cycling on/off ?

There's not very much volume in the RO-DI unit and tubes. Just a little
bit of leakage would drop the pressure enough to trigger the pump.

These pressure switches are rated at 40psi, but they probably turn off
at 40 and back on at 38.

Adding a reservoir allows more leakage without dropping the pressure
significantly.


I see... so you did not realize yet that it will not work this way :-)

Fair enough. But the pressure switch is after the RO/DI (not before).
It turns off the pump when there is a back pressure at 40psi which shuts
down the RO/DI unit.

I see what you're saying, and that would work if both the reservoir and
a 80psi pressure switch is located at the front. I don't think it's
done that way, because you wouldn't have a reservoir of processed water
ready to dispense at a tap.

That's my understanding, but it's subject to change. (Hopefully, this
weekend.)

--Kurt

"KurtG" wrote in message ...
Pszemol wrote:

So how would it prevent pump cycling on/off ?

There's not very much volume in the RO-DI unit and tubes. Just a little
bit of leakage would drop the pressure enough to trigger the pump.

These pressure switches are rated at 40psi, but they probably turn off
at 40 and back on at 38.

Adding a reservoir allows more leakage without dropping the pressure
significantly.

This is what I was describing before, but it only applies
to the situation when the tank/reservoir is in front of the membrane.
You plan to use it as a clean water reservoir, so it will be on the
other side.

I see... so you did not realize yet that it will not work this way :-)

Fair enough. But the pressure switch is after the RO/DI (not before).
It turns off the pump when there is a back pressure at 40psi which shuts
down the RO/DI unit.

OK, so you are just keeping the pump on all the time...
That is usually not necessary :-)

I see what you're saying, and that would work if both the reservoir and
a 80psi pressure switch is located at the front. I don't think it's
done that way, because you wouldn't have a reservoir of processed water
ready to dispense at a tap.

That's my understanding, but it's subject to change. (Hopefully, this
weekend.)

I had basically pump with a switch integrated with the pump.