The Steamboating Forum

DetroiTug/Ron,

The Southworth Pump casting kits are very reasonably priced.

I'm curious how many hours of machining it took to complete?

http://www.southworthengines.co.uk/steam-feed-pumps/
http://www.southworthengines.com/price-list/

-CB

" my boiler safety valve is set at 95 psi now how much psi would the hypro pump need to put water in the boiler? "

ANS: Pump discharge pressure will be 100 to 110 PSI

" is the pump running all the time? being on a v belt ?"

ANS; Typically yes, continuous running. If the pump is driven at just the right speed it keeps up with the boiler steam rate. Typical practice is to pump more than that, and open feedwater bypass when boiler level is high. Or you could blowdown boiler to lower level when level gets high, that will reduce impurities in the boiler.

" roughly how much water do you need to pump in a average size boiler per hour?

ANS: My steamer uses about 62 pounds of water per hour, which is almost exactly 1 cubic foot. That is 7.5 US Gallons per hour, 6 IMP Gallons per Hour. But I only make something less than one horsepower. Many boats typically will use twice as much, even more for a larger boat. See the FAQ section for better answer specific for your needs.

For your 21 ft boat, say 2 horsepower nominal, 3 horsepower max, about 120 pounds per Hour (PPH) feedwater flow, so size the pump for 150 PPH. One US Gallon per minute (USGPM) is very nearly 500 PPH, so you need 150/500 = 0.3 USGPM If the Hypro pump is rated for, say 2 USGPM at 1750 revolutions per minute (RPM), you only need 0.3/2 = 15% of pump rated speed, or 0.15 x 1750 = 262 RPM. Select pulleys to drive the pump at this speed.

fredrosse wrote:" my boiler safety valve is set at 95 psi now how much psi would the hypro pump need to put water in the boiler? "
ANS: Pump discharge pressure will be 100 to 110 PSI

Fred,

How did you come up with that figure of 100 to 110 PSI? Or +5 to +15 PSI over lighthouses MAWP.

I can find some datasheets online, and they say it will develop up to 500PSI.

My understanding(please correct if I am wrong) was that all your feed source needs to achieve is 1-3 PSI to open the check valve + unknown quantity of friction from piping/bends above the actual current boiler pressure. And depending on the feed source that could be more then that (which is ok - to a point).

I noted in DetroiTug/Ron's picture he had a water safety valve so that it won't build up enough pressure to damage the pump or his boiler. That's very proper!

The Hypro 5300 is more of series of pumps - and even the plain Hydro 5300 comes in several variations. I think it would be helpful if those who are using them share(Take a picture or write down the exact model) which is appropriate for this application in a steam boat. Or just post what features/options of a Hypro 5300 are good. http://www.pumpsandpressure.com/docs/pr ... atalog.pdf

-CB

The Hypro pumps are designed to run at 1700 rpm forever in applications like coin operated car washes so no worries about wearing them out. Grease the bugger once or twice a season.

Here's my setup on Folly:

The pump runs directly off of the crank end at engine speed. I use a flexible drive coupling to make life easier for me.

The output of the pump goes two ways. One line leads to a check valve and a ball valve and into the boiler. The other direction goes to a float valve in the hot well. If the hotwell level rises, the float valve closes and the pump output all goes to the boiler. If the hotwell level falls, the pump output goes into the hotwell. This way the hot well level is kept constant.

Since the total amount of water in the system is fixed, regulating the hot well level has the nice side effect of regulating the boiler level. The level is so constant that I am unable to see any variation except for consumption due to the safety valve or the whistle.

When the the boiler level drops a bit due to steam leaks, safety valve oafishness on my part and excessive tooting, I dump some more water in the hot well from a jug. Soon the boiler level climbs back where I want it.

All of this sounds very involved. The reality is that unless I am wasting water with the afore mentioned activities, I don't fuss with the system from hour to hour. Probably the biggest drawback is that I'm so used to its reliability that I get careless about watching the glass.

This works so well that I feel that it is an important argument for running condensing even on bodies of fresh water.

"How did you come up with that figure of 100 to 110 PSI? Or +5 to +15 PSI over lighthouses MAWP."

ANS: Just a guess on my part, a few PSI over the boiler operating pressure is typical. Of course if the piping is very undersized, then the pressure would be higher, but I have not seen that unless one closes the pump discharge valve.

"I can find some datasheets online, and they say it will develop up to 500PSI."

ANS; The HYPRO pumps will develop far more pressure than that if the discharge is throttled shut and there is no relief valve protecting the pump. However the amount of pressure actually developed depends on the piping and destination pressure the pump "sees" on its discharge path.

"My understanding(please correct if I am wrong) was that all your feed source needs to achieve is 1-3 PSI to open the check valve + unknown quantity of friction from piping/bends above the actual current boiler pressure. And depending on the feed source that could be more then that (which is ok - to a point). "

ANS; That is correct

"I noted in DetroiTug/Ron's picture he had a water safety valve so that it won't build up enough pressure to damage the pump or his boiler. That's very proper!"

ANS; Yes, more than very proper, but manditory! The rules of piping systems dictate that every piece of piping, and attached components, must be protected from exceeding their design pressure. If there is no isolation valve between the pump and the boiler, then the boiler safety valve can protect the pump, however the isolation valve between the pump and the boiler is required, so the pump needs another form of protection.

The most common form of protection is a relief valve on the pump discharge, which must be set at some pressure that is high enough so that relief does not occur in normal running. For example, on my boat, maximum boiler pressure is 100 PSI, and the feed pump (direct engine driven) discharge piping is fitted with a 200 PSI relief valve. There are other methods which can also work. My hand pump has no relief valve on the discharge, but, even if I stand on the pump working handle the pump will only produce about 400 PSI discharge pressure, and this piping is designed for 600 PSI, so that allows for protecting the piping. If a positive displacement pump such as the HYPRO is driven through a slip clutch which reliably limits the amount of torque that can be applied to the shaft, that could achieve the required level of protection.

"The Hypro 5300 is more of series of pumps - and even the plain Hydro 5300 comes in several variations. I think it would be helpful if those who are using them share(Take a picture or write down the exact model) which is appropriate for this application in a steam boat. Or just post what features/options of a Hypro 5300 are good. http://www.pumpsandpressure.com/docs/pr ... atalog.pdf"

ANS; Yes, the pump performance numbers can and do vary between pump models. The example I gave in the original post was 2 GPM, because that happens to be the pump I have on the shelf (I was lucky enough to see that pump in a store, new, for $59.95, so I bought it even tho I did not immediately need it). The sizing and determination of required drive RPM depends on the individual pump selected.

One final note, beyond the set pressure of a relief valve, the relief valve must also be large enough to pass the required flow. For most steamboat applications this is not an issue causing problems, merely because our boats are small. On the next steamboat project for me, I will be using the HYPRO pump, 2 GPM rated, but with 950 RPM speed, giving about 525 PPH. I typically use a small relief valve in the pump discharge, (obtained from W W Graingers for about $15) for small air compressor service, 1/8 inch pipe size. This is big enough for most small applications, but too small for the flow on that HYPRO at 950 RPM. In this case I will need a larger size valve, or installing a few of them in parallel on the pump discharge header.

One thing to keep in mind about piston pump discharge is that the pressure is not constant. It fluctuates between 0psi and roughly double the boiler pressure. If this were charted on a graph the baseline or average mean pressure would be somewhere near Fred"s estimate. And this varies with engine RPM/pump speed.

I have gauges installed on each pump. Originally I used 400 psi gauges and the fluctuations broke the needles off. I had to go to 1000 psi gauges. The single ram pump is really bad about this as half of the piston travel is in vacuum. The Hypro on the other hand is double acting so the output is more constant. I originally had 275psi relief valves and they would squirt at high rpm - had to go to 400 psi units and the ram pump will still squirt at very high rpm.

One fix or improvement here is a much larger shock arrestor. There are small vertical pieces of pipe on each one, but it needs a much larger accumulator right at each pump discharge and there is no room for them.

Ideally, a pump should run as slow as possible and slightly exceed the demand. Big pump running very slow. Like Wesley H's (tahoesteam) setup.

-Ron

I have a length of ordinary rubber coated air hose between the Hypro and the check valve. It absorbs the pulse quite well.

I had some feedwater gauge failures until found a fluid filled unit. The damping makes for more accurate readings as well.

cyberbadger wrote:DetroiTug/Ron,

The Southworth Pump casting kits are very reasonably priced.

I'm curious how many hours of machining it took to complete?

http://www.southworthengines.co.uk/steam-feed-pumps/
http://www.southworthengines.com/price-list/

-CB

If I remember correctly it took me 4-6 weeks to build two of them, that is occasional evenings and weekends - about 60 hours for one, machining it, assembling it, tweaking it etc. They are not an easy build, but very doable for a machinist of intermediate skills. Would take longer on manual machines.

Re: The price, the shipping is expensive. I think John said they were about 500 total each to get them to my door here in Detroit.

-Ron

DetroiTug wrote:One thing to keep in mind about piston pump discharge is that the pressure is not constant.

Lopez Mike wrote:I have a length of ordinary rubber coated air hose between the Hypro and the check valve. It absorbs the pulse quite well.

If you have an old school steam pump like the Marsh Simplex I've been restoring - they half a nice big bulb accumulator to smooth things out. Practically of course any air chamber would work. Not sure I like the idea of flexible hose doing that long term. But steamboaters make their own decisions. -CB

I've found that with feed pumps two things shut them up. The first is having the majority of the suction pipe in flexible hose, believe me, you can get good water hammer noise in a solid suction line. The second is having an air chamber on the discharge line. Just remember that air chambers do get water logged over time, so best to be able to empty them occasionally. I always run the discharge line from the pump in solid because of the pressures involved, although one vessel I run has a hydraulic hose on the discharge, which of course is fine for the pressure.
Daniel