No transients, in fact no difference between control and test at all. It may be that dissolving the LiAlH4 in Hexane so that it coated the orther ingredients as it dried denatured it too much. I do have another set up where I can control the hydrogen pressure but haven't used it this time. What's in the tube (which gets flushed with hydrogen before sealing) stays in there. The only thing I do in these type of tests is put a little chip of magnesium right at the bottom of the tube with wadding between it and the fuel proper. This is to mop up any stray oxygen.
I have a different batch of fuel brewing now, So many more tests planned, this is a simple and fast system.
Attached is a picture of the steel 'variable pressure' fuel containers in an original Mk1 Reactor. These were sold, but I have another pair that can be used in the current apparatus. They are fitted with silver-brazed 4mm OD gas/vacuum pipes (also stainless) which thanks to the very poor thermal conductivity of stainless steel can be coupled up with high-temperature silicon-rubber tubing. This kind of tubing is ok for pressures between 1mB and 3.0Bar, but for higher pressures could be fitted with suitable connectors for up to 6Bar - 84psi.
As you can see, the tubes fit into the 'hot cores' of the reactor, where they nudge up against a pair of thermocouples in the heart of the system. There is increased interest in monitoring Hydrogen pressure in fuel tubes, since this can be used to trigger reactions and also as the best indicator of the degree of hydrogen take-up (hydrogen loading) of the fuel.