I have recently acquired the above blow lamp.Do I need a washer between the vaporiser unit and the tank as parrafin leaks from it when pressurised.or is it an interference fit.i have no instructions from this unit.
No, you don't need any washers for that. It is also not an interference fit. It seals by metal-to-metal contact between the conical around the feed tube and the seating surface of the port as you tighten down the gland nut. Note that the threads perform no sealing function in this case. A common reason for not sealing is that the mating surfaces being nicked, unevenly deformed or the presence of deep scratches. Inspect those. Those can be corrected if they're not too severe. Another reason is that the threads might be worn or had been previously wrenched down cross-threaded or might have too much corrosion/oxidation products build-up in the threads. This would make it difficult or sometimes impossible to tighten the gland nut sufficiently. Hence, there would not be enough force to bring the mating surfaces into close/tight contact. Clean and repair any damaged threads if necessary. **Please note that it is necessary to tighten the nut hard enough for it to seal. It can sometimes be a little difficult to prevent the fuel tank from turning while wrenching down the nut.
I may have to try and get the two parts to seal better .I presume I could us fine grinding paste .the sort I use on my cylinder mower blades or reel blades in the states.
You'd need to inspect that area first to see if its really deformed or scratched before working it with grinding paste. Otherwise, you might not be tackling the right problem. Sometimes, all that's needed is to wrench the nut a little harder. Ensure that the threads and other metal are not damaged or filled with dirt before doing this.
