100W Tube, water cooling options?

[tdiaz]

Right now I have a submersible pump that after being hooked up manages to push just about a half gallon a minute through the tube, but the pump itself contributes to the heating of the water more than the laser tube does.

Perhaps adding a fan and transmission oil cooler would do the trick here.

But what kind of pump pushes water though that efficiently?

[Litografa]

As I understood you have chinese laser with glass tube. So best way is buy industrial water cooler. We have purchased our from
Richard.Zhao
Oversea Dept.
Sales Representative
ShenZhen Sunrise Industrial Co., Ltd.
Direct Line: +86-755-3393 5303
Fax: +86-755-2997 4586
Mobile: +86-134 2376 5300
E-mail: RichardZhao@dly-China.com
Web Site: http://dly-china.en.alibaba.com/

Expensive - $1000 in China, but you will save on laser tubes and engraving will be stabile.

[DaveDoesIT]

Originally Posted by tdiaz Right now I have a submersible pump that after being hooked up manages to push just about a half gallon a minute through the tube, but the pump itself contributes to the heating of the water more than the laser tube does. Perhaps adding a fan and transmission oil cooler would do the trick here. But what kind of pump pushes water though that efficiently?

Is the pump fully submerged in the water?

If it is heating the water then it may be defective.

There are a ton of submersible pumps from fountain pumps to bilge pumps to sump pumps. The GPMs range from very little to many hundreds.

For my 50 Watt, I use a 5 gallon bucket of water and a 3gpm submersible fountain pump and the max rise I get is about 10 degrees.

You can add an old oil cooler from the auto wreckers and an 8" or 10" fan for extra cooling.

You should also have a flow switch in circuit to shut off the laser if water flow is not sufficient. Also a water over-temp switch is a good idea too.

Dave

[tdiaz]

The pump is fully submerged, it's a Flowtec FP0S1300X

Amazon.com: Flotec FP0S1300X-03 Tempest 1/6 HP 1,470 GPH Utility Submersible Pump: Home Improvement

Amazon.com: Flotec FP0S1300X-03 Tempest 1/6 HP 1,470 GPH Utility Submersible Pump: Home Improvement

It's got a huge reduction on it, and is rated for 1470 GPM, but barely does .5GPM, not enough to trip my switch all the time. The reservoir is a 25 gallon sump.

I'm sure the huge reduction has something to do with this, but the tube has 1/4' inner diameter, so sooner or later it has to reduce.

I have not found anything that has a small hose that even comes close.

I'm probably not looking in the right places.

Here's some images of the installation:
http://17500mph.com/photos-3?g2_itemId=1266&g2_page=8

[DaveDoesIT]

Originally Posted by tdiaz It's got a huge reduction on it, and is rated for 1470 GPM, but barely does .5GPM, not enough to trip my switch all the time. The reservoir is a 25 gallon sump.

Hi,

I assume you mean 1470 GPH.

At that rate it is around 24 GPM which is way too much flow. Even if it were to flow at that rate, it would not be very effective at cooling the laser. The water would not have time to absorb a useful amount of heat to remove as it scoots through.

If the pump is restricted down then the pump will be cavitating. Most submersible pumps are a centrifugal type and will cavitate at the drop of a hat. That means running mostly in air as the flow through is not enough to keep the pump-chamber full for it to pump. That explains the getting hot.

Check the laser manual for the optimum flow rate and I am guessing 3 to 5 GPM.

Find a smaller submersible pump that is running unrestricted at about 3 to 5 GPM (180 to 300 GPH). Run it without restrictions. Something that size is going to have 3/8" or 1/2" inlets and outlets. Ideal sizes for easily available plastic tubing.

You are burning up the pump motor with the restricted flow and not doing your glass tube any favors either.

[tdiaz]

Yup, I meant GPH, I've got Liters per minute on my mind from the laser manual. The manual says 2 to 5 liters per minute.

With a half gallon being being 1.87 liters, so one gallon per minute would be close to the high end of what they want. I can't find any pump that does 60-100 gallons per hour that can pump itself out of it's own way.

The pumps from harbor freight seem to be in this category. A drunk can take care of natures calls faster.

[DaveDoesIT]

2 liters / minute = 0.528 GPM = 32 GPH
5 liters / minute = 1.321 GPM = 80 GPH

I'd try for something around 100 GPH to cover losses in the tubing and laser. It will be OK to throttle that down if you have to. My guess is it will be fine.

I can't remember the model number but I use fountain pumps from HF and from memory they cost about 15-bucks each.

[tdiaz]

So rather than the $24 HF model, I should get the least they have and it will work better because even the 200GPH one fails to do even .5 GPM? (15 gallons an hour)

That.. sorta makes sense if the back pressure is that profound. Perhaps it is.

I tried this one:
http://www.harborfreight.com/cpi/cta...emnumber=45305
and it didn't do squat,

I have this one now:
http://www.harborfreight.com/cpi/cta...emnumber=41287

..and it still hardly does .5GPM

I have 1/4" tubing on it, because the laser is that, I've got the output of the laser just stuck under the water level, about 12 inches long, total, the input is about 5 feet worth. The tubing is PVC vinyl so I know it's not collapsing on itself, except for two 3 inch sections at the tube because I'm not going to push PVC onto the glass. But they're 3/8 ID to fit over the other stuff and the tube fittings. No leaks.

The ones from Home Despot look about the same. Heck, the HF ones feel fairly heavy, well built for their size.

I need to establish that it is actually moving the amount of water it says, before going on. I've only hooked these little things up to the tube.

[tdiaz]

Okay, so what it really is - is a battle of the Marketing Dept. vs. Reality. Both will win.

I have been testing, unintentionally, but still real world, with the test bottle at 3 feet off the floor as the laser tube is also 3 feet off the floor, and the HF 190 GPH water pump in the bottom of the 5 gallon bucket.

So with just a 3/8" rubber tube on the pump I get the gallon container about 3/5ths full in 60 seconds.

If I put the bottle on the floor, where the rubber hose comes up out of the bucket, down onto the floor, 3 feet over to the bottle and then up into the gallon bottle, it fills the gallon in 50 seconds.

So perhaps I could hang the pump in the water just below the surface, so it's in effect about 1 foot below the laser tube level.

Changing the tube to .35 dia. 4 foot section, I can fill the bottle in 35 seconds with it on the floor and the tubing held in a single loop coil at bucket /bottle top height. Thats just over 100 GPH.

With the bottle at the 3 foot level, it fills it at 51 seconds.

(1 bottle in 60 seconds is 3.74 LPM which is middle of the road for the recommended flow rate)

If I take my existing electric 1400 GPH pump and the tubing right up to the laser tube inlet, I get 3.1 liters in 60 seconds. If I hook up the tube to it, I loose half that. I just put the caliper in the tube inlet, and it's .16 diameter. Not .25, so .. thats a major kink in the system.

Sigh.. I'm not sure anything is going to move through that any faster.