Water pump

[rangerssteamtoys]

I am making a monotube boiler and have a few questions about pumping water into it.

When pumping water into the tube, does the water have to be the same pressure as the steam?
Or can I use low pressure water?
What kind of pressure can I expect from 100' of 1/2" copper tubing?

Any help would be appreciated.

 

[Cedge]

Dang Ranger...
I wish I had you budget... 100' of 1/2 inch copper? I know what I paid last year for 50 ft of 3/16. :bow: :bow: :bow:

Steve
Who is claiming first in line for adoption

 

[rangerssteamtoys]

Dang Ranger...
I wish I had you budget... 100' of 1/2 inch copper? I know what I paid last year for 50 ft of 3/16. :bow: :bow: :bow:

Steve
Who is claiming first in line for adoption

Acutally I have 120' of 5/8" OD and 1/2" ID copper tubing.

I got this for FREE!!!!!!! Its from an old job that my dad did. He's in the construction buisness.

Back on topic- any body know anything about these boilers?

 

[ksouers]

Ranger,
Understand, the only steam plant and boiler I've ever worked on was built during World War II, and so was not completely modern. However, the principles are the same.

For any boiler that requires feed water, regardless of style, you should have a check valve on the inlet side. This is to ensure that pressure from the boiler does not push water backwards through the feed pump (if you have one) or whatever is supplying your feed water. On large boilers this check valve is adjustable (or automated) so as to match the use rate. As pressure in the boiler drops below the feed pressure the valve will open to allow more water to flow in, as the pressure increases the valve will close to stop the water flow.

Simple answer: Yes, your water supply pressure must exceed the boiler pressure in order to replace water already used.

On a low pressure boiler, say less than 35 PSI, city water pressure may be enough. If you a planning a closed-loop steam/water cycle, you have lots of headaches ahead of you. Best of luck.

Hope this helps.

 

[rangerssteamtoys]

Ok this is the pump I plan to buy http://cgi.ebay.com/Live-Steam-Engi...Z2594QQcmdZViewItemQQ_trksidZp1742.m153.l1262

Pre-machined and everything. I just need a bit of help with the math. CORRECT ME IF WRONG.
Can anyone confirm this
The pump has 3/8" stroke and 3/4" bore
The circumfrence of the 3/8" rod is 1.278097245, multiply (divide) that by the 3/4" stroke and get 1.5700796327 So that makes it 1.57 cubic inches of water in every stroke of the pump, multiply that by the average RPM of the engine 1000X1.57= 1570 cubic inches per minute. Divide by 231 (amount of cubc inches in a US liquid gallon)
1570/231=6.79 gallons per minute.

PLEASE CORRRECT ME. This equation sounds way off so I need help, I'm thinking it should be around one gallon per minute.

 

[Rog02]

Your math looks good, now work on your reading and you will be set! :big:

Basically you are going to have to jack the handle 1,000 times a minute to get that kind of gallonage out of that little HAND OPERATED pump. :wall:

Just kidding Ranger! If you decide to mechanize the pump then you can set the stroke length at what you want by adjusting crank pin offset there by adjusting the displaced volume output of the pump.

 

[rangerssteamtoys]

Just kidding Ranger! If you decide to mechanize the pump then you can set the stroke length at what you want by adjusting crank pin offset there by adjusting the displaced volume output of the pump.

What do you mean by adjusting crank pin offset? I plan to use an eccentric, or something similar.
My math is correct, thats great. So would this pump be suitable for filling 100' of 5/8" OD 1/2" ID copper tubing? It sounds like it to me, but in order to get the pump I must have confirmation from some of yall' so my dad will give me the OK to buy it.

 

[tel]

Hate to rain on yer parade, but the maths is waaaay off. No way can a 3/4" bore x 3/8" stroke equal 1.57 3"

I'll try and work up some real figures for you

 

[tel]

OK, the true volume per stroke is 0.16573660714285698 cubic inches, call it 0.166 for short.

Tuck this link away in your favourites - it's very handy for this sort of thing.

http://www.online-calculators.co.uk/volumetric/cylindervolume.php

 

[tel]

Arrrgh! It gets worse mate - you transposed the bore and stroke figures. Based on 3/8" bore and 3/4" stroke, the volume per stroke is actually 0.08286830357142849 (0.083) cubic inches. Got to be careful about that.

That said, the pump looks like value for money and should be adequate for the job in hand, remember that you are never going to have that pipe full, all you are doing is putting an amount of water into it that will flash to steam. You will need to power drive it tho'.

 

[ksouers]

Tel. Good catch there, mate.

 

[ksouers]

Ranger,
If you put a bellcrank in the linkage between the engine and pump you can adjust the stroke on the pump to match the volume of water you need to feed the boiler. Move the pump-side linkage close to the pivot to reduce the volume. Moving the same link closer to the driven link will increase your volume.

 

[SandyC]

Ok this is the pump I plan to buy http://cgi.ebay.com/Live-Steam-Engi...Z2594QQcmdZViewItemQQ_trksidZp1742.m153.l1262

Pre-machined and everything. I just need a bit of help with the math. CORRECT ME IF WRONG.
Can anyone confirm this
The pump has 3/8" stroke and 3/4" bore
The circumfrence of the 3/8" rod is 1.278097245, multiply (divide) that by the 3/4" stroke and get 1.5700796327 So that makes it 1.57 cubic inches of water in every stroke of the pump, multiply that by the average RPM of the engine 1000X1.57= 1570 cubic inches per minute. Divide by 231 (amount of cubc inches in a US liquid gallon)
1570/231=6.79 gallons per minute.

PLEASE CORRRECT ME. This equation sounds way off so I need help, I'm thinking it should be around one gallon per minute.   

Hi Ranger...... I have been watching this thread for some time now and I must congratulate you on your enthusiasm, it is great to see someone of your tender years getting stuck in to engineering, however, I regret to say your calculations are not quite correct.

The swept volume of the proposed water pump is considerably less than you have calculated...... you should take the CROSS sectional area of the ram and multiply by the stroke....not the circumference x stroke.

So: -
Area of 3/8" dia = 0.11045sq in x 0.75" stroke = 0.0828 cu in x 1000 strokes per minute = 82.8cu in per minute.

Divide by 231 (for US Gallons) = 0.358 galls per minute.


This would be the maximum volume of water pumped, however, you will probably not actually require this amount to all go through the coil and you will therefore need to install a water feed bypass system to return the unwanted amount to the feedwater tank....or, as Kevin has suggested, you can vary the pump rate.

To help you calculate the amount of water you actually need to put through the coil you must first calculate the amount of steam your engine actually requires in 1minute. and then divide this by the volume of steam produced by 1cu ins of water at the desired working pressure.
This will give you the number of cu in water your boiler must convert to steam per minute in order to satisfy your engines requirements.

At 150 psi, (still not really sure why you feel you need this high a pressure), 1cu ins of water will produce 169 cu in steam.

If you try and pump more water through the coil then all you will do is fail to evaporate it all and fill your engine with very hot water.
Conversly...if you pump to little you will end up with SUPERHEATED STEAM at the same pressure.

Monotube boilers (more correctly, steam generators) are not very user friendly when it comes to variable loading.
Controlling the steam output with a variable speed load, such as a steam engine, requires the use of: -

Either a variable firing rate....

Or a variable water flow....

Or a combination of both.

None of which are straight forward.

I hope this helps a little.

Best regards.

SandyC   ;D

 

[tel]

There are a couple of good books on the subject listed here;

http://www.chronos.ltd.uk/acatalog/Chronos_Catalogue_Books_from_TEE_Publishing_56.html

... scroll about 1/4 way down the page

 

[tel]

Tel. Good catch there, mate.

Thanks Kev, we can but try.

 

[SandyC]

;D

My apologies Tel and Kevin....Our posts seem to have clashed a bit there....you posted whilst I was still typing.

Hope you don't take it to heart.

SandyC ;D ;D

 

[ksouers]

No offense taken here, Sandy. I'm glad to see you on this thread (and the other). I need someone to catch MY mistakes, as well.

Actually, I'd been waiting for you to jump in at some point. Thanks for showing the water/steam ratio.

 

[rangerssteamtoys]

I pretty much knew that my calculations were WAY OFF. It sounded completley wrong at 6 gal a min. :
Now that I have proper calculations I can hopefully get that pump. It looked right at the start, but DAD said "NO, Its not going to give enough water to the boiler"

SandyC, I'm very thankful that you calculated it up and gave me the right answer. So this pump whould give enough water to the boiler, right? I MUST know, otherwise my Dad wont let me buy it. P.S. I want 150 psi becuase I'm working on a small steam buggy, I dont want to putter around. I got the need for speed and steam.

I'm working on coiling the copper for the boiler, does anyone know about type L copper water pipe?
I have figured out how to coil it now just need to get too it. The fire I plan to use is and electric blower and waste vegetable oil, I know a guy whoe melts iron with this setup so should get plenty of fire, I can also control the oil input by a needle valve. As for the water pump, I could connect a valve to the input and out put on the pump, I could control the water for the boiler. Once set right it will give just the perfect amount of water to the boiler because it will refill the boiler as fast as the engine uses it

JUST to confirm, this pump is a good pump to use right?

 

[Bookmaker]

Ranger,
P M Research has the same pump in kit form for $26.00 or as a machined assembly kit for $51.00.
Regards,
Roger

 

[tel]

No apology needed Sandy - the more the merrier, that's what makes this such a wonderful medium. I sure wish it had been about when I was about and looking for answers.

Yes mate - the pump looks to be quite adequate for the job.