Welcome, Guest
Username: Password: Secret Key Remember me
  • Page:
  • 1

TOPIC: Possible fuel?

Possible fuel? 1 year 4 days ago #830

  • Howes
  • Howes's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 3
  • Thank you received: 2
Has anyone tried the smoke pellets used for testing flues in gas installations? The PH type is a low temperature gas producing pellet with a formulation that comprises guanidine nitrate and potassium perchlorate. They seem to produce plenty of gas at about the right rate. The 13g pellets claim 18m^3 over 30 seconds. 13g is a bit big for a Jetex motor but something custom is not hard to make and smaller pellets are available. The AX type seems too slow burning. Here are the pellets:
www.arctic-hayes.com/Catalogue/Smoke-Pro...oke-Pellets-50-PH008

And the safety data sheet giving some clue about the formulation:
www.hvpsupplies.com/sites/45/_default/PH_5_13.pdf

Perhaps the manufacturer could be persuaded to make a few Jetex size pellets without the smoke additive?

Jonathan Howes

Please Log in or Create an account to join the conversation.

Last Edit: by Howes. Reason: Another typo

Possible fuel? 1 year 17 hours ago #831

  • rogersimmonds
  • rogersimmonds's Avatar
  • Offline
  • Administrator
  • Administrator
  • Posts: 307
  • Karma: 3
  • Thank you received: 46
Hi Jonathan,

many thanks for this and the link. As to whether these are a viable alternative to a genuine Jetex pellet - there is only one way to find out, which is to try one. A pellet could be cut down, I suppose, to fit a Jetex 50C, or would one fit - say - a PAA loader?

The original Jetex formulation was very carefully developed and I somehow doubt these are as meticulously produced.

I doubt the manufacturers would be interested in any proposal to change their production line.

Sorry to be somewhat negative, but whilst genuine Jetex pellets are readily available on eBay, I would be disinclined to put these in a motor! :unsure:

What we do lack is a viable (modern) source of fuse - any ideas?

Please Log in or Create an account to join the conversation.

Possible fuel? 11 months 4 weeks ago #832

  • Howes
  • Howes's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 3
  • Thank you received: 2
Hi Roger,

I have some on order. Tempted to try them in my old PAA loader although I think the 5gm pellets may be close to 50 size.
As for ignition, I have experimented with electrical ignition with reasonable success using Sebel fuel, although the most successful version was a faff to use since it involved a resitance wire (nichrome) making good contact with part of the case internally, with the case connected to one terminal and then passing a small insulated wire (standard enamelled copper) through the nozzle to meet the resistance wire internally to close the circuit. Only advantage seems to be that I don't need fuse and the enamelled wire will fit through the small nozzle. When it works ignition is obvious but it was a fiddle to get decent contact in the first place.

Where I want to go with the smoke pellets (which will be made to a very consistent spec for the usual product certification rule reasons) is a custom motor with a larger nozzle if possible. The 13g pellets are getting towards an inch in diameter (don't have any exact measurements yet). As they appear to leave a bit of solid residue after burning a tiny nozzle might not be a happy experience so these may be right for bigger motors/models. Electrical ignition will be easy at larger sizes but, of course, we shall see when I get a chance to try them. The basic Jetex concept of a spring-closed motor body was brilliant in its simplicity and safety and if these things work there may be a whole new development direction to take. I'll let you know how it goes.

Jonathan Howes
The following user(s) said Thank You: ahmetcalfe

Please Log in or Create an account to join the conversation.

Possible fuel? 11 months 4 weeks ago #833

  • rogersimmonds
  • rogersimmonds's Avatar
  • Offline
  • Administrator
  • Administrator
  • Posts: 307
  • Karma: 3
  • Thank you received: 46
Hi Jonathan,

I like your the electrical ignition system. As to your experiments with the smoke pellets, note these are not designed to be fired in a semi-sealed metal body, and the pressure will affect the rate of combustion. :dry: My advice as a Ph.D physical chemist is not (repeat, not) to do this unless you have access to a fume cupboard (the formulation contains ammonium chloride and the fumes are very nasty).
So please stand well back and wear safety glasses!


I look forward to your findings.:whistle:

Please Log in or Create an account to join the conversation.

Last Edit: by rogersimmonds.

Possible fuel? 11 months 4 weeks ago #834

  • Howes
  • Howes's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 3
  • Thank you received: 2
Hi Roger,

The amount of ammonium chloride is low (10mg/m^3 in the smoke emitted), also I have no intention of using these indoors although that is exactly how plumbers use them for testing flues and internal flows. They claim low toxicity but I would not think deliberate inhalation was a particularly smart move.

I am well aware of accelerated combustion under higher pressures (basic thermodynamics in a gas producing exothermic reaction) and so would never burn these in an unfused closed container. The Jetex system was very clever in that it makes the entire end cap into a safety valve retained by a light (for the area concerned) spring and significantly limits pressure. I am extremely wary of stability of combustion (being an ageing Aero-Engineer still with a full complement of limbs and fingers). I'll let you know how it goes.
The following user(s) said Thank You: rogersimmonds

Please Log in or Create an account to join the conversation.

  • Page:
  • 1
Time to create page: 0.173 seconds
Powered by Kunena Forum