Water Pumps and switches

[MicroBill]

I've tried the pump that came with the machine as well as another pump that I picked up at the local home improvement store. Both pumps work. However, I can't get either pump to provide enough pressure to activate a *flow switch*. Just to emphasize - I'm NOT talking about a pressure switch or flow meter. I've tried the flow switch available here at LO as well as other types found elsewhere - like the white plastic one and even a stainless steel one that works similarly to the white plastic one. I just don't see how I can get enough pressure given the diameter of the tubing going in an out of the laser tube - as well as the diameter of the cooling line within the tube itself.

Can someone show me a pump and flow switch combination that works?

thanks,

Bill

[seeigecannon]

I got one of the white flow switches off of Amazon and I had to remove a coil from the spring to make it work.

[Tech_Marco]

Pump:
http://www.lightobject.com/10Lmin-158GP ... -P511.aspx

Water sensor:
http://www.lightobject.com/Water-flow-O ... -P680.aspx

or

http://www.lightobject.com/Water-flow-p ... -P815.aspx


Marco

[SScnc]

Bill, how far below your laser and switch is your pump ?

All pumps have a specific "head" (height of water column above pump, basically). The higher you go, the less flow and pressure.

[MicroBill]

Bill, how far below your laser and switch is your pump ?

All pumps have a specific "head" (height of water column above pump, basically). The higher you go, the less flow and pressure.

The machine is at countertop height and the bucket is on the floor. Right now I haven't even hooked up the laser tube to the cooling line. I'm just running a loop and trying to get a flow switch to fire. I think our head loss here is due to the tubing diameter and the sharp reduction in tube diameter (at the fitting) rather than head loss due to elevation.

[SScnc]

You may be right but my stock pump is doing it through the 1/4" tubing with no problem running my flow counter. Head on mine is about 28". If I go more than that, I too have problems such as you're having.

So, I think you should try raising your bucket. HTH

[MicroBill]

I cut off a few coils from the spring as seeigecannon suggested and the switch is now working.

I probably could've left the spring out entirely as the flow would raise the little plunger "pill" inside the sensor and gravity would let it fall when the pump is shut off. The flow switch is mounted vertically on the pump so I probably could get away with taking that spring out.

I have a flow counter but am not using it for now. I'm not ready to count pulses and measure flow. Just want to know if the water is flowing - period. Hence the switch and not the meter.

Next problem...playing around with that cold water (RV antifreeze actually) in the forty-some degree garage makes me afraid to run the thing on cold days. I know it's not like the cold water will hit a hot tube since the coolant will be flowing before the tube gets hot and they'll warm up together. But still... I worry.

Bill

[DonL]

I cut off a few coils from the spring as seeigecannon suggested and the switch is now working.

I probably could've left the spring out entirely as the flow would raise the little plunger "pill" inside the sensor and gravity would let it fall when the pump is shut off. The flow switch is mounted vertically on the pump so I probably could get away with taking that spring out.

I have a flow counter but am not using it for now. I'm not ready to count pulses and measure flow. Just want to know if the water is flowing - period. Hence the switch and not the meter.

Next problem...playing around with that cold water (RV antifreeze actually) in the forty-some degree garage makes me afraid to run the thing on cold days. I know it's not like the cold water will hit a hot tube since the coolant will be flowing before the tube gets hot and they'll warm up together. But still... I worry.

Bill

Check out Tech_Marco's post on thermal shock... He recommends that a tube not be used below 15 degrees C (59 F) I think he is explaining that it is not the cold water hitting a hot tube, it is the tube heating up faster than the coolant and if the coolant is too cold it will cause too much stress on the thin glass coils and they could crack. He had a customer fire up his machine in the cold, at or just below 15 degrees C (59 F), and the coolant was also the same temp, but his tube could not take the stress and filled up with coolant after the coolant line cracked while cutting.

[MicroBill]

Thanks Don! REAL good to know.

Bill

[MicroBill]

I think I'll ad a heater to my cooler.

Seriously - since it gets pretty cold in the garage sometimes, I might as well stick a submersible aquarium heater into my coolant bucket and leave the pump and heater on. Leaving it on and pumnong is really no different than having an aquarium.

Any thoughts?

Bill

[DonL]

I think I'll ad a heater to my cooler.

Seriously - since it gets pretty cold in the garage sometimes, I might as well stick a submersible aquarium heater into my coolant bucket and leave the pump and heater on. Leaving it on and pumnong is really no different than having an aquarium.

Any thoughts?

Bill

You have to watch that ambient temp too, I would recomend you fire up a heater for about 30 min before you start lasering so there is no shock. Plus it will be more comfortable