2" Burrell Kit 21

HI GUYS, JUST GOT AROUND TO BUILDING UP OUR CLACK VALVES THIS AFTERNOON. WHEN WE TOOK THE BODIES OUT OF THE BAG, ONE HAS WHITE WAXY LOOKING STUFF IN THE 'TURN' VALVE CHAMBER, THE OTHER DIDN'T, I GUESS ITS LEFT OVER FROM THE LOST WAX CASTING PROCESS. THE VALVE DOESN'T FIT IN THERE ANYWAY, AND IT HAS BLOCKED THE HOLES, THINK IT WILL COME OUT OK WHEN NEED TO. SO STARTED PUTTING THE OTHER ONE TOGETHER (WITHOUT THE WAX), ALL GOOD BUT WE NOTICED THAT THE 'TURN' PART IS FAIRLY LOOSE IN THE BORE (TOP AND BOTTOM MOVEMENT SORTED BY THE GRAPITE STRING), BUT I CAN SEE THAT WATER WOULD BYPASS THE VALVE - SLOWER OF COURSE- WHEN IT IS SHUT. IS THIS RIGHT STEVE ???

WHAT HAVE THE OTHER BUILDERS FOUND ON THIS PLEASE ??

BUNGLE

Bungle,the white stuff you refer to is a seal of some sorts to keep things steam tight I think.
I left it in myself,just cutting it down enough for the thread to be exposed and cleared the holes running through the clack valve body.
I've used graphite yarn when screwing the check valve cock nut (BU22110) into place

Hope this helps,perhaps Steve will clear this up for us.

cheer's Tony

THANKS TONY, MAKES SENCE, BUT WHY DOES ONLY ONE OF MINE HAVE IT IN ??????????
IT DOESN'T MENTION IT EITHER WAY IN THE INSTRUCTIONS !!

STEVE HELP !!!!

BUNGLE

hi all, i now have the tender on and have fitted the reverser and gear guard. Spent an hour today setting the slide valve timing and had to file down the brass valve holder to stop the lock nut hitting the rear of the steam chest.
Tony, what size of compressor did you buy? i now need to get one so i can test on air. My valve excentrics are also loose but the water pump on is fine, any ideas why this is the case as they were all fitted in the same way.

Hi Forge,being tight with cash at the moment I only spent £100 on a small compressor at my local Halfords.It a SIP Airmate TN 1.5/6.0.
The 1.5 refers to the size of the motor and 6.0 refers to the size of the receiver (6 litres).
It runs nicely pumping out a steady 50psi and the engine runs OK on this,there is one problem though,I need to put a water trap on it.
Like I've said,it's only a cheapy,but it does the job for me as I dont have much space at home,and nieghbour's who like to complain even if you fart too loud.

cheer's Tony

Bungle

When I went to HOLLOWELL I spoke to Steve about these clack valves. He stated that they would normally be left in the open position. If you close them the injector one or pump one wont be able to top up the boiler with water. The stuff inside the body is like a PTFE and is put in there then drilled out to the size of the valve. The valves do go in with a bit of pressure (I squeezed mine in in the vice) after first clearing out the threads, The second one I put in was a bit loose and leaked past. When the boiler is pressured with the valves open the ball bearing in the chamber should prevent the steam being forced back into the injector/pump. I was therefore not too concerned about the valves not being steam tight providing it does not leak out past the gland at the top.

I did query how the injector or pump forces water into the boiler when it has to overcome the pressure already in the boiler. eg if the boiler is at 75psi how can the injector which is pressurised by the boiler (75psi) overcome the boilers pressure to lift the ball bearings in the clack valves and thus force water in when the are all at the same pressure.

Steve baffled me with the explanation and below is an extract from a website about how they work :-

Injectors work because steam under the same pressure and conditions flows from a contracted nozzle at a much greater velocity than water. The steam cone, or nozzle, regulates the quantity of steam used by the injector. It is both convergent and divergent in order to direct the flow of steam into the combining cone and give it the maximum possible velocity.

The condensation of the steam jet and transfer of its energy to the water takes place in the combining cone which receives the steam and water. In condensing, the steam gives up its velocity to the water, which is then further accelerated by the vacuum in the combining cone caused by the reduction in volume of the steam when condensed by the water. At the inlet end is a jet consisting of a mixture of steam and water, while the outlet end has a jet of hot water flowing at high velocity but very low pressure.

The combining cone is split lengthwise for part of its length and hinged at one end. Should the water supply be interupted the injector stops working as condensation does not occur. Steam when there is no water to condense it can lift the flap and freely escape to atmosphere via the overflow valve until normal water flow is resumed.

The jet passes across a gap after exiting the combining cone and before entering the delivery nozzle. This overflow gap is necessary for disposing of the steam and water before the steam is condensed when starting the injector.

The jet of water is at its maximum velocity as it enters the delivery nozzle, and as it passes through the nozzle and delivery cone its velocity decreases as the bore of the cone increases, so that the pressure will increase until it is sufficient to overcome the boiler pressure and the water can enter the boiler.

When working, the injector would tend draw in air via the overflow pipe, hence the need for a valve on the overflow to prevent this while allowing a free escape for any overflow of water and steam.

That's about as clear as mud as well then!!

Can't wait to get the injector now to see all that working (Ha Ha)

Cheers

Alan

THANKS FOR THAT AL, I DID KNOW THAT THEY WOULD REMAIN OPEN ALL THE TIME IN PRACTICE. I HAVE ALSO READ THE EXPLAINTIONS OF HOW INJECTORS WORKS, AND LIKE YOU MOST OF IT WENT OVER MY HEAD !!!!!!! ONE OF THOSE THINGS THAT YOU JUST ACCEPT THAT THATS HOW IT WORKS AND DON'T THINK TO DEEPLY ABOUT I GUESS !!!
SO IT LOOKS LIKE I SHOULD HAVE HAD THE PTFE IN BOTH OF MY CLACK VALVE BODIES, I'LL TALK TO STEVE TOMORROW WHEN I GET CHANCE. AS YOU SAY GUESS IT'S NOT OVERLY IMPORTANT, BUT THEN ON THE OTHER HAND STW WOULDN'T HAVE GONE TO THE EXPENSE OF PUTTING IT THERE IF THEY FELT IT WASN'T NEEDED.

THANKS AL AND TONY FOR COMING BACK TO ME ON THAT.

REGARDS
BUNGLE