Never mind the draincocks

[nigel jones 5Participant @nigeljones5]

Im building a 71/4 Invicta, or a rough interpretation at least. The original didnt have drain cocks on the cylinders – do I need them? Not intended to be a sunday kiddy chuffer but I dont want to get showered in gooey black stuff either – your thoughts please.

[nigel jones 5Participant @nigeljones5]

[stan pearson 1Participant @stanpearson1]

Hi Fizzy

Yes all steam engines should have drain cocks to get rid of condensed water which can destroy your engine.

Stan

[Paul LousickParticipant @paullousick59116]

Getting showered in "gooey black stuff" is part of owning a steam engine. Wearing a white shirt is not recommended. As Fizzy has said, all steam engines should have drain cocks to drain any condensed water in the cylinders. Water will not compress and if it is inside of the cylinder will jam the piston, stopping the reciprocating motion of the engine. The energy in the rotating flywheel will either bend the piston rod or push the cover plate or gland off the end of the steam chest.

Condensate forms in the supply lines and cylinder when it is cold and not up to operating temperature and the drain cocks should always be open when starting an engine and slowly turned over until there is no water or moisture coming from them. Then they can be closed and the engine brought up to speed. It is good practice to always leave the cocks open when stationary and only close them after checking for condensate when starting.

Paul.

Edited By Paul Lousick on 26/12/2013 11:01:46

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Fizzy ,

LBSC version of Invicta may not have had cylinder drain cocks but the real engine probably did .
Not nescessarily what we would recognise on later engines but probably some provision was made .

Slow running low pressure wet steam engines with slide valves do not of absolute nescessity have to have drain valves – between the slide valve lifting , large clearances and a multitude of leak paths there is little likelihood of damage .

Damage on full size engines usually occurred whilst actually running along and where a slug of water went over into the cylinders . Relief valves are needed to deal with this problem and these were fitted to most modern engines .

Cylinder drains would only help in this case if they happened to be open .

LBSC’s Invicta is so nearly freelance anyway that fitting drain cocks would not spoil the appearance so I personally would fit them .

No linkage back to the cab though – old engine men were a hardy lot and they opened and closed any valves by hand whilst running along side !

A quite common feature on early engines was the single dump valve fitted either on bottom of common steam chest ( where used ) or on base of blast pipe . Hot steam was run through to waste and both generally hotted up everything in the cylinder area and prevented large slugs of condensate from going up the chimney .

Regards ,

MikeW

[Halton TankParticipant @haltontank]

If you have a slide valve engine then you can get away without having drain cocks, but you will splattered and may have to give your engine a push start to get going.

My Halton Tank was fitted with manually operated drain cocks but no operating lever and linkage was fitted. I used showered when I started if the engine remained stationary for a period. I have since fitted automatic drain cocks and I stopped getting showered with the added bonus of not having to remember to operate the things.

I would recommend that you fit automatic draincocks as they are easy to make and you have to bother with any controls or linkages.

Regards

Luigi

[stan pearson 1Participant @stanpearson1]

Relief valves are not as important as drain valves on a slide valve engine, in theory the pressure will lift the slide off its seat so the water can escape but it will bend the opperating rod.

Regards

Stan

[julian atkinsParticipant @julianatkins58923]

stan,

erm… why will the operating rod bend (i assume you mean valve spindle)?

i think fizzy will have already found the answer to his question by way of fitting cylinder drain cocks.

cheers,

julian

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