Reducing flow in 12v parts washer pump

[mangocrazy]

A while back I bought a 240v parts washer off eBay, effectively identical to the Clarke CW1D floor standing item, but painted orange instead of red. When I came to use it, I found that it need around 20 litres of solution in the tank before the fluid level was high enough for the pump inlet to draw anything other than fresh air. I regarded this as a long way from satisfactory and decided to modify the pump arrangement.

I decided to go with a 12v pump as they were a) readily available and b) less potentially harmful if I cocked anything up. The one I chose was this item:

http://www.ebay.co.uk/itm/Diesel-Fuel-Transfer-Pump-200-GPH-Refueling-12v-/370538859446

I acquired a nice chunky (110Ah) 12v battery (also off ebay) for a very reasonable £25 and tried the new arrangement out for the first time last night. It all worked beautifully, I'm glad to say, but if anything it worked too well...

The pressure the pump provides causes quite a large amount of splashback when the jet of fluid hits anything solid, and consequently a fair amount of degreasing fluid found its way onto the floor, me, adjacent walls etc.

Is there any way of reducing the pressure by means of a resistor or potentiometer in circuit, and if so how would I go about this? Some kind of variable resistor would be good, so I can dial in the amount of flow/pressure required. A self-contained unit, that I can wire into and out of would be perfect. The specs for the pump are as follows:

Connections: 1/2" (13mm) Hose
Dimensions: 165mm long x 38mm diameter
Maximum Current: 4.5 amps
Output: up to 200 gph (760 lph)
11 PSI pressure
32' (9.7m) Head
3ft (1mtr cable length)
Continuous Duty rating but should not be run dry for long periods
Actual Weight: 0.22 Kg (Approx. 0.42 Kg packed)

Any suggestions gratefully received...

 

[ibrooks]

For speed control on a DC motor you really want a PWM controller (Pulse Width Modulation). It Pulses the full voltage at a variable duty cycle rather than giving the motor a reduced voltage. They are far more controllable than just sticking a resistor in the line and not expensive.

http://www.ebay.co.uk/itm/New-10A-D...ial_Automation_Control_ET&hash=item35d1ac133b

Or if you want to save a few quid and can wait for it.

http://www.ebay.co.uk/itm/Hi-Q-Puls...ial_Automation_Control_ET&hash=item53fd594922

Iain

 

[Fintray]

Put a "T" piece into the supply pipe with a valve to adjust the return flow to the tank.

 

[rtbcomp]

Put a "T" piece into the supply pipe with a valve to adjust the return flow to the tank.

+1

 

[Wallace]

I had the same problem with the original pump and fitted a valve in the flexy tube to restrict the flow. What sort of filtration are you using on that pump?

 

[mangocrazy]

I like both approaches equally, to be honest, although I'm probably tending towards the lower-tech of the two (T-piece and valve). The pump has basic filtration provided by the plastic case on the base, with small holes through which the fluid is sucked. I've added a layer of foam to that to filter out the smaller lumps. When I drain the tank I filter it through a couple of coffee filters in a funnel back into the containers.

What sort of valve would you use with the T-piece arrangement? The hose I'm using for the main flow is 12mm (1/2"). Would you use an equal or unequal tee?

 

[Wallace]

From memory I used a 1/4" BSP ball valve from my box of air/plumbing spares (no T piece) so it just restricts flow, I would take a photo but the machine is packed away at the moment and not accessible. The original pump is on it's last legs and needs a better filter system, I plan on converting to an external tank with a simple weir system. I use Jizer so the final wash is done with hot water or thinners/brake cleaner and airline depending on the parts and how clean they need to be.

 

[rtbcomp]

Restring the flow could overload the pump. The bypass method is kinder!

 

[PhillipM]

I would just bolt an aerator to the end of the pipe.

 

[mangocrazy]

An aerator wouldn't easily fit onto the delivery nozzle. I think I'm going to buy a couple of unequal tees (12 x 10 x 12 and 12 x 8 x 12) to start off with and see which gives the best outlet pressure at the delivery nozzle. It's cheap and easy to do.

 

[AndyStobbs]

Buy one tee and a valve. Infinite adjustment.

 

[MrFluffy]

My commercial parts cleaner has a ball valve you can adjust flow rate of the fluid with, although its air powered (no problem with sparks...) so it doesnt get upset if you stall it. But then, thats exactly how 99% of machine suds pumps regulate flow too.

 

[bill_gj]

The PWM route gets my vote. I've used these a few times and it works well.
I recently bought one like the second link, above, and it does the job well, although a bigger heatsink is needed.

 

[BrokenBiker]

id go with the t and valve.