feed water by-pass

[johnp]

Thanks Mike

The hot well, condenser, vacuum pump thing might be a little ahead of me. This is my first steamboat/engine build, I've only physically seen one steam boat at the Toronto boat show a couple weeks ago, (other than the Internet). I'm trying to keep it as simple as I can. However with 3 ways to get water in the boiler, feed water heater, stack blower, whistle, safety,blowdown valve. It's getting busy. Any pointers are always welcome.

John

[DetroiTug]

John,

In the pic you can see how I plumbed my non-condensing system feed pump.



There is a 1/4" T in the bottom of the pump connected to the inline check going in to the pump, one side of the T is for the raw water line coming from the strainer, and the other side of the T, a drain valve (hidden from view in this pic). Then a 1/4" cross on top of the pump for feedline, bypass and relief valve. Get a relief valve set for about 250 psi. it's just an air compressor relief valve. The manual bypass is just a 1/4" gate valve.

When I put in, I just open the drain and that bleeds the air and allows water up to the bottom of the pump. This set up seems to work very well.

I would go ahead and go to Home Depot or similar and put a shock arrester on the exit side of the pump, they make small ones for ice makers. I used a simple length of pipe that should capture air and act as a cushion, but the jury is still out whether or not its doing the job.

Oh one other thing on the exit side of the pump, use a 500 or so PSI pressure gauge as a pump indicator, the fluctuations when pumping will be slight, and not damage the needle, I've smoked two 250 psi gauges already, the needle whipping wildly back and forth.

-Ron

[fredrosse]

Bart, good point about arranging the bypass to avoid air binding. I designed my pumps to be self venting, with the recirculation (bypass) arranged such that any air would get passed on to the boiler, rather than the recirculation path. But I am sure many actual arrangements would not suit these conditions.

I also like the concept of the two pumps connected in series, using the hand pump to purge the engine driven pump. In the case of the Margaret S., the hand pump is rather large displacement (1.374 bore x 5 inch stroke), while the checks and water passages through the engine driven pump (0.75 bore, 1.3 stroke) are small, and would slow down the working of the hand pump cosiderably if all the hand pump water were to pass through the small pump's passages. I may pipe it up so that I can select the discharge path of the hand pump, either thru the engine driven feed pump or directly to the boiler feed header.

[Lopez Mike]

See, John? Lots of good ideas on here. Probably more good experience available here that anywhere else.

That said, I dunno about having the manual and engine driven pumps in series. The advantages are as claimed. But it would seem as though you would loose a lot of redundancy. There are a number of components in common. A failure of any one of those would put you in a difficult position with both pumps out of service.

Injectors have worked well for me in larger sizes but little ones often seem to pack up when needed due to hot water feed. Lifting ones are the worst which is what John would need for lake feed.

One of the things we have preached often is to have at least two independent means of getting water into the boiler. I wouldn't want to inadvertently give that up.

Thoughts?

Mike

[barts]

This is how I run the Otter; the automatic bypass means I don't have to touch the boiler for 10 or 15 minutes at a time; the water level is automatically regulated. I add some from time to time to make up for water use by the steam atomizing burner. It is way easier to run the boat this way; I've tried both open loop and closed loop, and the simple float-controlled bypass valve is a big improvement.

- Bart

[DetroiTug]

Mike,

That is how Chief's pumps are plumbed, independently, each can be isolated from the other. Only the main engine driven pump goes through an economizer. The manual pump is a much larger line and volume, and goes straight to the boiler, it's sole purpose is emergency back up and get some water in the boiler and get back to the dock. There is a 12 volt circulating pump under the floor for filling the boiler at start up, it too is isolated from the other two means of getting water in to the boiler. ( I used two, too and to in the same sentence)

-Ron

[barts]

I only have one water source - hotwell or tank, so both pumps pull from the same suction. In my experience the common pump failure mode is a hung check valve that prevents pump from pumping; this is most often cause by airlock. Yes, if the pump physically broke or the plumbing broke or ...
things would stop - but I'm 10 seconds away from no fire (oil fired), so I can afford to resolve the common problem at the expense of a longer repair cycle in the uncommon case.

- Bart

[johnp]

Holy info, thanks guys.

I tried my bypass tonight and it seems to work. I sort of made a manifold which all three pumps connect to each having its own isolation valve. The bypass is also on the manifold and when open slightly reduces flow of water. The bottom valve is the feed pump, the middle is the hand pump, and the top is the steam injector, still lots to do but with a little description i think you can see what i'm doing. The bottom gate valve is my bypass valve it goes back to the feed pump. The supply line goes up through the check valve to the top of the boiler, around a coil for feed water heater and down the other side through a valve and in the bottom of the boiler.
If all this works ok my next challenge is a neat and tidy way to supply all these pumps with a check valve before each. I got frustrated tonight so packed it in tonight. I'm thinking my one main supply1/2" from the seacock through a strainer then another "manifold" feeding three 3/8" flapper type checks.

What do you guys think?

[artemis]

...What do you guys think?

I think that those quarter turn ball valves down near the deck area need to be placed so that a pants cuff or little kids hand doesn't inadvertently turn them off or on.