marki Posted August 22, 2015 Report Share Posted August 22, 2015 Hi All. As the title says, I'm in the process of fitting a fuel pressure gauge in the Cab and need to screw in the adaptor just before the Metering unit. What should I use on the thread, will PTFE be any good ? TA Mark Quote Link to post Share on other sites
Peter Cobbold Posted August 22, 2015 Report Share Posted August 22, 2015 Mark, I would not fit a fuel pressure gauge in the cockpit. Oil pressure gauges have been known to fail - it makes a mess. Pressurised fuel spraying into the cockpit......doesn't bear thinking about. An electronic sensor and gauge is what you need. Peter Quote Link to post Share on other sites
marki Posted August 22, 2015 Author Report Share Posted August 22, 2015 Hi Peter. That's what I've got. Mark Quote Link to post Share on other sites
John Bracher Posted August 22, 2015 Report Share Posted August 22, 2015 Hi Mark. I am thinking of fitting a simlar 'accessory'. Could you advise what/where you found a suitable gauge please? Most of the ones I have are found are not really suitable, awkward, or just plain Fugly! Thanks! Quote Link to post Share on other sites
marki Posted August 22, 2015 Author Report Share Posted August 22, 2015 Hi John. Still work in progress at the moment. I will post pics etc if it all works. Mark Quote Link to post Share on other sites
Peter Cobbold Posted August 22, 2015 Report Share Posted August 22, 2015 Hi Peter. That's what I've got. Mark Mark, My apologies. One of the Loctites I think: http://www.loctite.co.uk/thread-sealing-9170.htm Teflon tape might release threads into MU. Peter Quote Link to post Share on other sites
marki Posted August 22, 2015 Author Report Share Posted August 22, 2015 Thanks Peter. Yes that was my worry as well, I'll look at the Loctite. Thanks again Mark Quote Link to post Share on other sites
John Bracher Posted August 22, 2015 Report Share Posted August 22, 2015 Would blue Hylomar do the job? Seems to hold against most 'fuel/oil' type situations if you let it 'go off' a little before closing unions? Quote Link to post Share on other sites
John Bracher Posted August 22, 2015 Report Share Posted August 22, 2015 Also (sorry, premature posting syndrome). When looking for advice on fuel hose/sealing/joints/fittings etc, I found a farm machinery shop very helpful! Find one that services combines/JCBs etc (BIG kit, not lawnmowers), as they have good stocks/advice on suitable products/solutions. Quote Link to post Share on other sites
john.r.davies Posted August 22, 2015 Report Share Posted August 22, 2015 (edited) Here is the Hylomar website on the Blue and the Red: http://hylomar.com/hylomar-product-range/gasket-jointing-compounds/ Â Blue would seem to be the bunny, but I'd be concerned that more than the very mearest smear would exude beads that got into the fuel flow. Like brake joints, that don't need a sealant, fuel joints should be designed to seal without. Â I have a pressure sensor under the bonnet, and the joints to that are assembled dry, as are all the joints in my fuel system. John Edited August 22, 2015 by john.r.davies Quote Link to post Share on other sites
peejay4A Posted August 22, 2015 Report Share Posted August 22, 2015 Liquid ptfe will do the job. Quote Link to post Share on other sites
marki Posted August 22, 2015 Author Report Share Posted August 22, 2015 Hi John. How do you seal the threads ? Mark. Â Hi Pete. I thought of liquid PTFE but still concerned if fuel would dissolve etc. Mark Quote Link to post Share on other sites
AlanT Posted August 22, 2015 Report Share Posted August 22, 2015 You want the grade of Loctite that is used on hydraulic pipework. This dissolves if any get into the fluid so it won't gum things up. Quote Link to post Share on other sites
marki Posted August 22, 2015 Author Report Share Posted August 22, 2015 Hi Alan. Any idea how to find the correct grade ? Mark Quote Link to post Share on other sites
stillp Posted August 22, 2015 Report Share Posted August 22, 2015 Try here: http://www.loctite.co.uk/thread-sealing-9170.htm   Pete Quote Link to post Share on other sites
AndrewMAshton Posted August 22, 2015 Report Share Posted August 22, 2015 Hello, the problem with PTFE tape is there are different types, white is for water and I think it dissolves in petrol, try this, Permatex 80019 Aviation Form-A-Gasket No. 3 Sealant Liquid Gasket Maker 4oz., it is used in the marine world and is well thought of, cheers, Andrew Quote Link to post Share on other sites
marki Posted August 22, 2015 Author Report Share Posted August 22, 2015 Hi Andrew. After a few searches this is the stuff I have also came up with, resistant to all fuel types. Cheers Mark Quote Link to post Share on other sites
john.r.davies Posted August 23, 2015 Report Share Posted August 23, 2015 (edited) Hi John. How do you seal the threads ? Mark. Â You don't, Mark, any more than you seal the threads in a brake connection. The end to the line and the face of the brake component, eg slave cylinder, are shaped to squeeze together and seal. The engineering term is a "compression seal" and the line may be shaped or an 'olive' used to promote the seal. Â As I say, my entire fuel system is connected by dry joints, and don't leak a bit! Â My oil cooler has hoses with connectors swaged on, made by a local hydraulics firm. Hydraulics operate at pressures that would explode any cars fuel, oil or any other system, and they are connected dry. Â John Edited August 23, 2015 by john.r.davies Quote Link to post Share on other sites
marki Posted August 23, 2015 Author Report Share Posted August 23, 2015 Hi John. I'm trying to seal a tapered thread,unfortunately not a compression. Mark Quote Link to post Share on other sites
john.r.davies Posted August 23, 2015 Report Share Posted August 23, 2015 Then I''d suggest seeking a different connection. Brake fluid is nasty, cooling water can scald, but spraying fuel is dangerous! Â John Quote Link to post Share on other sites
Andy Moltu Posted August 23, 2015 Report Share Posted August 23, 2015 Permatex 59214 or Loctite 542 are fuel safe hydraulic thread sealants. PTFE tape is petrol resistant but not had much luvk using it to seal fine threads at the pressures in the Lucas PI system. Â Blue Hylomar isn't intended for continuous contact with fuel. Quote Link to post Share on other sites
graeme Posted August 23, 2015 Report Share Posted August 23, 2015 A correctly installed tapered fitting with PTFE paste or the Permatex mentioned above should be good for 5,000 PSIG. I have used many tapered fittings in the Oil & gas industry without problem. Â A PI system is relatively low pressure. Â Cheers Graeme Quote Link to post Share on other sites
marki Posted August 23, 2015 Author Report Share Posted August 23, 2015 Thanks guys. Permetex would appear to be slightly cheaper. Mark Quote Link to post Share on other sites
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