about 30 years ago I bought several paraffin lamps /irons / stoves / blow lamps / and heaters. And now have decided to bring them out the attic and get them working. I am hoping someone can answer my query although it does relate to a Bladin blow lamp. If I pressure it there is no shut off valve so the pressure will just release through the nozzle even if not ignited, so I have to pre heat and then pressure before igniting the vapour. With specific regard to the `pump`when I pump it it puts pressure into the blow lamp but is the pump tube airtight or should it be, in other words is the leather washer airtight OR is the pump unit as a whole itself airtight as it does have a washer where it screws in. Hoping I have made this clear enough to understand.
Welcome, @scudo Is this a kerosene (paraffin) blow lamp? There should be a non-return valve (NRV) at the bottom of the pump tube. It is this that stops the pressure exiting back through the pump tube, not the pump cup. If the NRV is not working the pressure (and fuel) will leak back into the pump tube. Let me know if that helps. Cheers Tony
What Tony said. The pump or leather aren't strictly air tight. They are not responsible for preventing air or fuel from the tank to escape. It is the non-return valve that matters for this function. If any pressure is lost via the pump, the usual reason would be a faulty NRV or the rubber pip had hardened or disintegrated, hence, preventing any sealing function. That's assuming the pump tube doesn't have any cracks or pin holes and the solder joints aren't compromised in any way.
OK thanks for replies. I think I now understand. The plunger tube that goes down in to the body has a non return valve at the end of it but would not be visible unless I take the tube out. I was only looking at the plunger when pulled out of the tube which is why I couldn't grasp how it was air tight. I will fire it up when I get some Meth for the preheat and see what happens.
A better idea would be to use some soap bubbles to check for leaks before you fire it up. Take the pump out of the tube and soak the leather cup in oil for at laeast an hour. Massage the leather with you fingers a bit to make sure it is pliable then reinstall. Put a few drops of liquid dishwashing soap and some water in a small plastic squeeze bottle. Shake vigorously to make suds in the bottle. With the stove empty of fuel, pump up the stove with several pumps and apply some soap suds around the pump shaft. If the NRV is leaking you will see larger bubbles form in the soap suds.
Good idea, I will need to try and seal the `flame` nozzle though as that does not have a shut off valve on this model so any pressure would continually leak our the `flame` nozzle.
Tested with bubbles, I would say a little leakage, I have now taken the tube out (see image) where do I go from here how do I dismantle the return valve, it appears there is a thin cap on the end, does this screw off?
I've not seen a NRV like that before, they usually look like one or the other of these two Either way, they come apart and look like this, there will be a cork or rubber pip in the small brass cup on the end of the spring. With your example, I'd see if the end cap unscrews - it may be a bayonet fixing
Yes it looks like the only option. I'll give it a go tomorrow. I am a bit nervous though as I half expect something will break off.
I managed to unscrew the end cap, using a couple of nails and pliers which thankfully worked as per image. Can I reverse the cork pip and reuse or must it be replaced?
You can either reverse the pip or smooth the existing face with fine sandpaper. The important part is to make sure that it's "square-on" in the cup. You could also stretch the spring but only a little.
ok, thanks for your help with this,I think I have got familiar now with how it all works and should manage a successful repair. Thanks all for the input.
I'd be tempted to replace the cork with a circle of rubber, but thats easy for me as i have a set of hole punches and a few sheets of viton rubber. If you did decide to do that, I could make a couple for you FOC if you'd like.
