Return-Path: Received: from SMTP02.INFOAVE.NET ([165.166.0.27] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 611164 for flyrotary@lancaironline.net; Tue, 18 Jan 2005 00:13:55 -0500 Received-SPF: none receiver=logan.com; client-ip=165.166.0.27; envelope-from=jewen@comporium.net Received: from home1 ([206.74.87.186]) by SMTP00.InfoAve.Net (PMDF V6.2-X31 #30986) with SMTP id <01LJQ6QA8VNU9DBM0W@SMTP00.InfoAve.Net> for flyrotary@lancaironline.net; Tue, 18 Jan 2005 00:13:13 -0500 (EST) Date: Tue, 18 Jan 2005 00:11:32 -0500 From: Joe Subject: Re: [FlyRotary] EGT Thermocouple construction procedure To: Rotary motors in aircraft Message-id: <001101c4fd1c$2cd47810$6432a8c0@home1> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-Mailer: Microsoft Outlook Express 6.00.2800.1437 Content-type: multipart/alternative; boundary="----=_NextPart_000_000E_01C4FCF2.43E43150" X-Priority: 3 X-MSMail-priority: Normal References: This is a multi-part message in MIME format. ------=_NextPart_000_000E_01C4FCF2.43E43150 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Todd, Very nice job on this procedure. =20 I just wanted to note that anyone using the type of TC (grounded = junction) described in this procedure, should check that their = instrument(s) are suitable for use with grounded junction TCs. Some = instrumentation, multiplexes multiple TCs to a single AD (analog to = digital converter) and if only one leg of the TC channel is internally = switched to the AD, ground loops can occur which may adversely affect = the display value. With non isolated multiplexed instruments, isolated = junction TCs are needed. Joe ----- Original Message -----=20 From: Todd Bartrim=20 To: Rotary motors in aircraft=20 Sent: Monday, January 17, 2005 2:21 AM Subject: [FlyRotary] EGT Thermocouple construction procedure Today I typed up the procedure for making your own TC probes. It = took me longer to type it than it takes to make 2 of them. I hope this = is clear enough to follow. I know that a few pics taken during = construction would be worth much more, however I didn't have a camera = with me at work when I made these. EGT Thermocouple construction procedure =20 Materials Required; 1. .25"x0.49" 316SS tubing 2. Solid "K" type thermocouple wire (positive & negative) 3. 1/8" ceramic TC wire spacers. Some of these don't seem to be = made uniformly, (at least not the ones I had on hand) and you may need = to sort through a bunch in order to find some that will fit snugly = inside a =BC" SS tube. They can be found at = http://www.omega.com/pptst/ORX_INSULATORS.html 4. "K" type extension wire (preferably multi strand) 5. Silver Solder 6. 316SS 1/16" TIG welding rod 7. Tightly wound spring with =BC" ID, approx 3" - 6" long 8. Tightly wound spring with =BC" OD approx 3" - 6" long 9. Parker or Sweglok tube fitting =BC"tube X 1/8" NPT 10. Electrical insulator cloth. =20 =20 =20 Procedure; 1.. Using a stainless tube cutter (extra hard wheel), cut tube to = desired length for TC probe. Deburr one end only, leaving the other end = with burr only allowing a small hole in end of tube.=20 2.. Cut + & - solid TC wires several inches longer than probe = length.=20 3.. Twist the ends of these wires several times to create the TC = junction=20 4.. Slide several ceramic spacers onto the TC wire.=20 5.. Insert this TC into the SS tube in the deburred end, until the = twisted TC junction extends approx 1/8" through the small burred hole on = the other end of the tube.=20 6.. Lightly clamp in vice with tip facing up.=20 7.. TIG weld closed the top of the tube, including in the weld, the = twisted pair of TC wires. This requires a delicate touch and very little = filler rod. Best to practice on some scrap tube ends first. There should = be no filler material extending past the OD of the tube. Lightly grind = or file off any excess if necessary. Clean up using wire wheel if = desired. This is your grounded tip thermocouple.=20 8.. Slide on several more inches of ceramic spacers on to the TC = wires=20 9.. Strip approx 1" of the outer sheath off of the extension wire = and =BD" of the insulation off the ends of the extension wires.=20 10.. Silver solder these extension wires to the TC wires. Ensure the = polarity of wires is correct. Red is always negative in TC's. The = negative wire in "K" type is also magnetic while the positive wire is = non-magnetic.=20 11.. Wrap these junctions with an electrical fibrecloth insulator, = ensuring to keep wrap tight (1/4" OD). There are probably other = acceptable ways to insulate this junction including putty or ceramic, = but this worked well for me.=20 12.. Slide the tightly wound spring with =BC" ID over the extension = wire, over the solder splice to the TC wires (ensure insulator wrap = slides securely inside spring), over ceramic spacers and finally onto = the end of the =BC" tube. You will need to "screw" this spring onto the = tube end, which it will easily do, using the spring coils as "threads". = This will securely hold spring onto the probe and provide a high = temperature, flexible sheath over the TC wire splice, to provide = mechanical protection.=20 13.. Slide smaller spring with the =BC" ID over the extension wire. = This should fit quite tightly to the extension wire, so a "screwing" = action may be required to slide it along the wire. When you reach the = larger spring, the 2 springs can be "screwed" together with the OD of = the coils of the smaller spring mating perfectly with the ID of the = coils of the larger spring. Screw these together for 1" - 2" or just = short of the splice location.=20 14.. The tube fitting has a shoulder in it, preventing the tubing = from passing though. This is there as normally this fitting is just used = to couple tube to pipe. This shoulder needs to be removed by drilling = out with a =BC" drill bit. Once removed this fitting will slide easily = over the end of the TC probe.=20 15.. Drill & tap the manifold in the desired location with a 1/8" = NPT hole. The surface of the manifold can be extremely hard, preventing = even the best drill bits from starting a hole. Use an angle grinder to = just take a little off the surface... use this as an opportunity to make = a flat surface to insert the tube fitting in until the outer shoulder = contacts evenly.=20 16.. Once the tube fitting has been fully seated, check the inside = of the manifold to see if any part of the threaded fitting protrudes = into the exhaust path. Grind off with a die grinder if necessary.=20 17.. With ferrule and tube nut loosely screwed onto the tube = fitting, insert TC probe until the tip is just protruding into the = exhaust gas path - or to desired depth.=20 18.. Tighten tube nut approx, 1.5 - 2 turns. This will seat the = ferrule permanently onto the tube. If you tighten too much you will = squeeze the tube to point where you will begin to hear the ceramic wire = spacers begin to crack under the pressure.=20 19.. Loosening the tube nut allows the TC to be removed.=20 20.. That's it you're done. Todd Bartrim RV9Endurance 13B Turbo Rotary C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "The world will always have a place for those that bring = hard work and determination to the things they do." ------=_NextPart_000_000E_01C4FCF2.43E43150 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Todd,
Very nice job on this procedure. =20
 
I just wanted to note that anyone using = the type of=20 TC (grounded junction) described in this procedure, should check = that their=20 instrument(s) are suitable for use with grounded junction TCs.  = Some=20 instrumentation, multiplexes multiple TCs to a single AD (analog to = digital=20 converter) and if only one leg of the TC channel is internally switched = to the=20 AD, ground loops can occur which may adversely affect the display=20 value.  With non isolated multiplexed instruments, isolated = junction TCs=20 are needed.
Joe
----- Original Message -----
From:=20 Todd = Bartrim=20
Sent: Monday, January 17, 2005 = 2:21=20 AM
Subject: [FlyRotary] EGT = Thermocouple=20 construction procedure

   =20 Today I typed up the procedure for making your own TC probes. It took = me=20 longer to type it than it takes to make 2 of them. I hope this is = clear enough=20 to follow. I know that a few pics taken during construction would be = worth=20 much more, however I didn't have a camera with me at work when I made=20 these.
 

EGT Thermocouple = construction=20 procedure

 

Materials Required;

1.     =20 .25"x0.49" 316SS tubing

2.     =20 Solid "K" type thermocouple wire (positive & = negative)

3.     =20 1/8" ceramic TC wire spacers. Some of these = don't seem to=20 be made uniformly, (at least not the ones I had on hand) and you may = need to=20 sort through a bunch in order to find some that will fit snugly inside = a =BC" SS=20 tube. They can be found at=20 http://www.omega.com/pptst/ORX_INSULATORS.html

4.     =20 "K" type extension wire (preferably multi=20 strand)

5.     =20 Silver Solder

6.     =20 316SS 1/16" TIG welding rod

7.     =20 Tightly wound spring with =BC" ID, approx 3" - = 6"=20 long

8.     =20 Tightly wound spring with =BC" OD approx 3" - 6" = long

9.     =20 Parker or Sweglok tube fitting =BC"tube X 1/8"=20 NPT

10.  Electrical=20 insulator cloth.

 

 

 

Procedure;

  1. Using a stainless tube cutter = (extra hard=20 wheel), cut tube to desired length for TC probe. Deburr one end = only,=20 leaving the other end with burr only allowing a small hole in end of = tube.=20
  2. Cut + & - solid TC wires = several inches=20 longer than probe length.=20
  3. Twist the ends of these wires = several times to=20 create the TC junction=20
  4. Slide several ceramic spacers onto = the TC=20 wire.=20
  5. Insert this TC into the SS tube in = the=20 deburred end, until the twisted TC junction extends approx 1/8" = through the=20 small burred hole on the other end of the tube.=20
  6. Lightly clamp in vice with tip = facing up.=20
  7. TIG weld closed the top of the = tube, including=20 in the weld, the twisted pair of TC wires. This requires a delicate = touch=20 and very little filler rod. Best to practice on some scrap tube ends = first.=20 There should be no filler material extending past the OD of the = tube.=20 Lightly grind or file off any excess if necessary. Clean up using = wire wheel=20 if desired. This is your grounded tip thermocouple.=20
  8. Slide on several more inches of = ceramic=20 spacers on to the TC wires=20
  9. Strip approx 1" of the outer = sheath off of the=20 extension wire and =BD" of the insulation off the ends of the = extension=20 wires.=20
  10. Silver solder these extension = wires to the TC=20 wires. Ensure the polarity of wires is correct. Red is always = negative in=20 TC's. The negative wire in "K" type is also magnetic while the = positive wire=20 is non-magnetic.=20
  11. Wrap these junctions with an = electrical=20 fibrecloth insulator, ensuring to keep wrap tight (1/4" OD). There = are=20 probably other acceptable ways to insulate this junction including = putty or=20 ceramic, but this worked well for me.=20
  12. Slide the tightly wound spring = with =BC" ID over=20 the extension wire, over the solder splice to the TC wires (ensure = insulator=20 wrap slides securely inside spring), over ceramic spacers and = finally onto=20 the end of the =BC" tube. You will need to "screw" this spring onto = the tube=20 end, which it will easily do, using the spring coils as "threads". = This will=20 securely hold spring onto the probe and provide a high temperature, = flexible=20 sheath over the TC wire splice, to provide mechanical = protection.=20
  13. Slide smaller spring with the =BC" = ID over the=20 extension wire. This should fit quite tightly to the extension wire, = so a=20 "screwing" action may be required to slide it along the wire. When = you reach=20 the larger spring, the 2 springs can be "screwed" together with the = OD of=20 the coils of the smaller spring mating perfectly with the ID of the = coils of=20 the larger spring. Screw these together for 1" - 2" or just short of = the=20 splice location.=20
  14. The tube fitting has a shoulder in = it,=20 preventing the tubing from passing though. This is there as normally = this=20 fitting is just used to couple tube to pipe. This shoulder needs to = be=20 removed by drilling out with a =BC" drill bit. Once removed this = fitting will=20 slide easily over the end of the TC probe.=20
  15. Drill & tap the manifold in = the desired=20 location with a 1/8" NPT hole. The surface of the manifold can be = extremely=20 hard, preventing even the best drill bits from starting a hole. Use = an angle=20 grinder to just take a little off the surface... use this as an = opportunity=20 to make a flat surface to insert the tube fitting in until the outer = shoulder contacts evenly.=20
  16. Once the tube fitting has been = fully seated,=20 check the inside of the manifold to see if any part of the threaded = fitting=20 protrudes into the exhaust path. Grind off with a die grinder if=20 necessary.=20
  17. With ferrule and tube nut loosely = screwed onto=20 the tube fitting, insert TC probe until the tip is just protruding = into the=20 exhaust gas path - or to desired depth.=20
  18. Tighten tube nut approx, 1.5 - 2 = turns. This=20 will seat the ferrule permanently onto the tube. If you tighten too = much you=20 will squeeze the tube to point where you will begin to hear the = ceramic wire=20 spacers begin to crack under the pressure.=20
  19. Loosening the tube nut allows the = TC to be=20 removed.=20
  20. That's it you're=20 done.
Todd Bartrim
 
RV9Endurance
13B Turbo Rotary
C-FSTB
http://www3.telus.= net/haywire/RV-9/C-FSTB.htm
 
          &nbs= p; =20 "The world will always have a place for those that bring hard work and = determination to the things they do."
 
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