Correct ! Because of the design, it's easy to distort the base plate which tears the soldered seam between base plate and sidewall. From a post earlier this year In the early days the rule of thumb was if it's not getting any brighter, stop pumping. Later, about the time the X246B came into being, Tilley recommended with a full tank (1.5 pints) give a maximum of 100 pump strokes. (Or words to that effect). This is important especially with the X246B as the base of the tank can easily be distorted by over pressuring.
Indeed not and most manufacturers give some indication of a full working pressure by fitting a pressure indicator/gauge or like Tilley stating a number of pump strokes. The Tilley pressure indicator is very unreliable so counting pump strokes with a full tank is safer particularly as tanks made after 1957 are prone to fail if you over pump. Tilley working pressure is 2bar or about 30psi but the pump tube will top out at around 55psi and for a later Tilley likely to damage the base seam. With 30floz of kero and 100 pump strokes Tilley X246 reaches the 2 bar working pressure and if your lamp has a pressure tit you can re-set it by filing it down until the inner and outer are level. In general it is always best to follow the instructions. I know Bialaddin instructions say 20 to 30 pumps for the 320 but it's the same basic tank as model 310 and those instructions state "There is no danger of over pumping". They also say there is no advantage in excessive pumping but that is rubbish and up to a point more pressure always delivers more cp. ::Neil::
Hi Dan ... I concur at all what has been said above in the posts , but really I do believe that excessive pumping is not required at all on your M320 Vapalux , from my own experience and I have two of these these robust lamps , the most critical issues are 1. the Non return valve mechanism at the foot of the pump tube , inside the little seal / spring and aperture must be exceptionally clean... and the sealing washer perfect ... this ensures perfect pressure within the tank font. Also 2. the leather washer must be very supple and well oiled very often they can be too stiff/rigid and not and suitable . They must also spin freely when tightened up on the lock nut and rotate around the pump shaft. check for foreign debris in the pump shaft and clean. + oil . Check for loss of pressure ... water dunk test to check other seals .. tank seals / vapouriser seals...Dan on operation ... for me 6 + pumps for initial light , wait about 30 secs .. further 20 pumps ... finish off with a further 15 pumps ... it is tickety boo for at least 2/3 hours intense light ... I use 28 sec kero more often than Premium paraffin ... you can modify Chinese mantles to fit no probs .... enjoy your lantern