Reflex gauge

[artemis]

Custom machining of a special flange, works every time! Nice work.

Just earlier this month is a discussion about blowdown, including gauge blowdown, I assume you have followed that thread. Being able to blow/clean the gauge glass while underway is necessary.

BTW, Mike, I too have a bare circular glass, and also need the plexiglass shield, but to get that fitted, I need to get a roundtuit, anyone know where to get one of these??

I've gone through a number of "roundtoit"s over the years. I used to buy them at the hardware store where I got a couple of board stretches and one wire stretcher. They're no longer in business (sigh)

Note to Lopez Mike - For all kinds of piping, valves and whistle valves, tube, gasket material, packing try Paramount Supply http://www.paramountsupply.com/ - they have a branch in Bellingham.

[marinesteam]

I've gone through a number of "roundtoit"s over the years. I used to buy them at the hardware store where I got a couple of board stretches and one wire stretcher. They're no longer in business (sigh)

No doubt, put out of business as part of a grand conspiracy by the lumber and wire manufacturers?

Ken

[steamboatjack]

Gents,
Speaking now as a boiler inspector:- I would not be happy with any of the above! A correct pattern gauge glass is made using isolation cocks and blank plugs co axial with the cock axis, This is so in the open condition there is a clear path and with the boiler dry, the path can be “rodded through” via the blank plugs with out having to totally dismantle. Use of globe valves does not allow such a clear path.
The picture showing a water column:- I have two comments here, first the gauge looks to me like one I would use on a water tank? Second, the connection between the column and the boiler should also be fitted with isolation cocks to allow “cross blowing”
and the column should have a drain cock. The arrangement shown would not be allowed on a ship.
Yes I know that hobby steam boats are not ships, but the gauge glass is the most important fitting on a boiler with perhaps the exception of the safety valve. Why not fit the correct items which are available at least here in the UK? Yes they are not cheap but then lives are not either.
Reflex glasses are made down to 115mm (glass length) These are often used in refrigeration condensers, It is not difficult the make a bronze glass housing with tubular ends to fit a conventional tube glass gauge set (see photos of Whippet).
The supplier of quality gauge glasses is :-
http://www.chanterbiomed.co.uk

[DetroiTug]

Hi Jack,

Sage advice. The valves used are Series 300 "rising stem gate valves" Steam rated. Removing the gauge is just eight bolts should the need arise, actually less work than replacing the glass itself.

This "rodding through", although this may be an accepted practice, seems rather suspect. Shoving a rod of steel I presume over bronze and across and possibly into the gate and bronze seating surface in a valve would run the risk of damaging them.

-Ron

[barts]

The other thing to keep in mind is that we're not in mid-ocean or mid-gale, and the degree of serviceability needed under pressure is much less than in shipboard installations. I simply don't consider changing the reflex gage glass under pressure to be an important design consideration. I don't carry a spare in the boat, for example, and have rarely been more than a mile or two away from land. On our small (19 ') boat, if the reflex gage begins to leak, I shut down the fire, and find a place to tie up/drop anchor as needed. There are lots of other single points of failure in the boat's power plant as we all have learned over time.

A serviceable set of paddles is a important safety item, too.

- Bart

[DetroiTug]

Anything that cannot be isolated is part of the pressure vessel (as you know). Being able to control the volume on larger boilers is essential. Smaller volume boilers as in perhaps the Ofeldt or similar, probably not that big of a deal, by the time the valves are closed, the boiler would be empty anyway. Some small 5-7 hp Ofeldts only hold about 1-2 gallons of water. My boiler holds about 40 gallons.

Some of the steam car guys use a bottom blow or emergency evacuation. Just a big valve to dump the boiler straight down, to put out a possible gas or kerosene fire in the burner and empty the boiler.

-Ron

[gondolier88]

Anything that cannot be isolated is part of the pressure vessel (as you know). Being able to control the volume on larger boilers is essential. Smaller volume boilers as in perhaps the Ofeldt or similar, probably not that big of a deal, by the time the valves are closed, the boiler would be empty anyway. Some small 5-7 hp Ofeldts only hold about 1-2 gallons of water. My boiler holds about 40 gallons.

-Ron

That's ok then, that's only 64,000gal steam through the glass if it blows! Gate valves are a unreliable anywhere you need a 100% positive shutdown, especially on gauge glasses because it will fur up, our gauge glasses get blown down twice a day, and still need cleaning at the end of season. You only need a small piece of grit on the seat and you will not isolate your glass.

Rodding is a completely safe and acceptable practice, usually a knitting needle does the job perfectly, anything with a slightly rounded and with a long tapered point on will do- again, why do you need to rod- because of furring up. Rodding isn't a problem in standard gauge glass isolating valves as they use packed taper cocks (old type) or graphite sleeved plug cocks, either tapered or straight, which incidentally are not prone to failure to shut off due to small bits of grit etc.

As I suggested at the top, the only remedy for your problem is a shorter glass, or to make/find a connection in the smokebox for the top pipework to come off, or you could make a manifold where the safety valve comes off.

While it's fine putting it out into the public domain you are confident in a non-standard repair on your boiler, stating you won't have a problem as you won't be far from shore doesn't instill confidence in any potential steamboaters who may be thinking of joining our hobby, or indeed thinking of buying a steamboat made entirely by it's previous owner.

Greg

[Lopez Mike]

Lots of advice here. Some of it conflicting but that's nothing new,

Greg, I would not connect the top of the gauge to the safety valve. In fact, our operating regulations for the Northwest Steam Society prohibit any sharing with the safety valve.

For something to make you sweat in a cold room, my boat had a shut off valve for the safety valve when I bought it. Yeow!

I'm not that worried about failure of a reflex gauge glass. They might crack but would only leak and make you quit for the day. My tubular glass is much more problematical. The valves on it are built with rather restricted flow for just that reason. And have flow stopper balls as well.

The one thing on which I differ with Ron over is the lack of a blow down valve for the gauge. I just don't trust things that much and I get a small bit of security from the little ritual of checking both the top and bottom valve functions every time I begin a days operation.

In fact, it is included as part of our annual certification for operation at club events. After the hydro test we require a gauge test including a blow down followed by a safety valve test.

Actually, with my careless firing, my safety valve gets lots of testing!

Mike

[gondolier88]

A tee'd manifold with isolation to the gauge, and no isolation to the SV should be allowed by your regulations, SV's are taken off manifolds on an awful lot of boats, and I can't understand why a gauge glass connection would not be allowed to share a manifold with a SV as there would never be a continuous draw-off, and certainly never enough to stop the SV functioning properly, expecially if the Tee is of the same bore as the SV is connected to at the moment- perhaps this would be worth clarifying with the NWSS? Having another look at your photo, it would seem to give you the required amount of height.

It staggers belief that people get through life getting away with doing things like having an isolating valve on a boiler, funny isn't it that 100 years ago most layman would recognise a safety valve and it's function, a little like today when most motorists can tell an illegal number plate on a car for example.

Greg

[artemis]

A tee'd manifold with isolation to the gauge, and no isolation to the SV should be allowed by your regulations, SV's are taken off manifolds on an awful lot of boats, and I can't understand why a gauge glass connection would not be allowed to share a manifold with a SV as there would never be a continuous draw-off, and certainly never enough to stop the SV functioning properly, expecially if the Tee is of the same bore as the SV is connected to at the moment- perhaps this would be worth clarifying with the NWSS? Having another look at your photo, it would seem to give you the required amount of height.

It staggers belief that people get through life getting away with doing things like having an isolating valve on a boiler, funny isn't it that 100 years ago most layman would recognise a safety valve and it's function, a little like today when most motorists can tell an illegal number plate on a car for example.

Greg

ASME code for power boilers - which is rigorously enforced in the USA - particularly in a civil or criminal case in a court of law - specifically states that a safety valve shall be directly connected to the boiler with with a pipe which is as short and direct as possible; of a size that is not less than that of the input for the safety valve and that no additional valves or other fittings/accessories shall be fitted to this pipe.

A safety valve MAY NOT be connected to a manifold. Think about this for a minute and you will understand why a safety alve, which needs to measure the HIGHEST pressure in the boiler should not share it's measuring steam with anything else at any time.