---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Thu 01/31/13: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:06 AM - Re: pneumatic system woes (Cpayne) 2. 06:17 AM - Re: Re: pneumatic system woes (Byron M Fox) 3. 08:40 AM - Re: pneumatic system woes (Walter Lannon) 4. 09:20 AM - Re: pneumatic system woes (Hank Gibson) 5. 09:42 AM - Re: pneumatic system woes (doug sapp) 6. 09:53 AM - Re: pneumatic system woes (Tom Elliott) 7. 09:54 AM - Re: pneumatic system woes (William Halverson) 8. 10:37 AM - Re: pneumatic system woes (A. Dennis Savarese) 9. 10:48 AM - Re: pneumatic system woes (A. Dennis Savarese) 10. 11:16 AM - Re: pneumatic system woes (William Halverson) 11. 12:19 PM - Re: pneumatic system woes (Elmar & Manuela Hegenauer) ________________________________ Message 1 _____________________________________ Time: 04:06:04 AM PST US From: Cpayne Subject: Yak-List: Re: pneumatic system woes Check valves seals should last a lot longer. Use high strength, high temp, oil-resistant synthetic material with about a 60-70 durometer(A) material. Buna-N grades like Nitrile, silicone rubber or EPDM selected to meet the task. I believe I stamped mine from weather resistant EPDM. Craig Payne ________________________________ Message 2 _____________________________________ Time: 06:17:46 AM PST US Subject: Re: Yak-List: Re: pneumatic system woes From: Byron M Fox Craig, where did you find an off-the-shelf stamp or punch to make your seals? Blitz Fox 415-307-2405 On Jan 31, 2013, at 4:03 AM, Cpayne wrote: > > Check valves seals should last a lot longer. Use high strength, high temp, oil-resistant synthetic material with about a 60-70 durometer(A) material. Buna-N grades like Nitrile, silicone rubber or EPDM selected to meet the task. I believe I stamped mine from weather resistant EPDM. > > Craig Payne > > > > ________________________________ Message 3 _____________________________________ Time: 08:40:00 AM PST US From: "Walter Lannon" Subject: Re: Yak-List: pneumatic system woes Elmar; I have been making them from 3/32" neoprene. They don't last forever but at least a few years. Recently changed to VITON. We'll see how that stands up. The material must be a nitrile, not natural, rubber of a fairly high Durometer reading - about 70 as I recall. Walt -----Original Message----- From: Elmar & Manuela Hegenauer Sent: Wednesday, January 30, 2013 8:39 PM Subject: Yak-List: pneumatic system woes Keith and others, I usually have my all my check valves on my CJ overhauled with every annual. For that purpose I have stocked up springs and rubber pads but I can't remember the supplier :-( To make a long story short, all those rubber pads I have used over the years have failed sooner or later between the annuals, so I got curious. Now let's get technical, Brian Lloyd are you still alive? The rubber pad in a CJ check valve has a nominal diameter of 13 mm what translates into a area of circle of roughly 132 square millimetres or 1.32 square centimetres. The physical weight introduced to this little piece of rubber is around 66kgs/145 lbs at 50 bars/700 psi. That is a lot of pressure on a small rubber disc going against the sharp and perforated seat of the lower check valve assembly. I have done some tests in my workshop at factor 1.5 over a period of several months and the rubber pads all disintegrated (with and without air tool oil), the material seems to be too thin and soft!!! Any constructive thoughts or ideas? cheers Elmar ________________________________ Message 4 _____________________________________ Time: 09:20:08 AM PST US Subject: Re: Yak-List: pneumatic system woes From: Hank Gibson Can you all share the details of how the proper diameter disc is stamped out; type of tool, etc? Thanks- Hoot Sent from my iPhone On Jan 31, 2013, at 11:36 AM, "Walter Lannon" wrote: > > Elmar; > > I have been making them from 3/32" neoprene. They don't last forever but at least a few years. Recently changed to VITON. We'll see how that stands up. > > The material must be a nitrile, not natural, rubber of a fairly high Durometer reading - about 70 as I recall. > > Walt > > -----Original Message----- From: Elmar & Manuela Hegenauer > Sent: Wednesday, January 30, 2013 8:39 PM > To: yak-list@matronics.com > Subject: Yak-List: pneumatic system woes > > > Keith and others, > > I usually have my all my check valves > on my CJ overhauled with every annual. > > For that purpose I have stocked up springs > and rubber pads but I can't remember the > supplier :-( > > To make a long story short, all those rubber > pads I have used over the years have failed > sooner or later between the annuals, so I > got curious. > > Now let's get technical, Brian Lloyd are > you still alive? > > The rubber pad in a CJ check valve has a > nominal diameter of 13 mm what translates > into a area of circle of roughly 132 square > millimetres or 1.32 square centimetres. > > The physical weight introduced to this little > piece of rubber is around 66kgs/145 lbs at > 50 bars/700 psi. > > That is a lot of pressure on a small rubber disc > going against the sharp and perforated > seat of the lower check valve assembly. > > I have done some tests in my workshop at factor > 1.5 over a period of several months and the rubber > pads all disintegrated (with and without air tool oil), > the material seems to be too thin and soft!!! > > Any constructive thoughts or ideas? > > cheers > > Elmar > > > > > > > > ________________________________ Message 5 _____________________________________ Time: 09:42:30 AM PST US Subject: Re: Yak-List: pneumatic system woes From: doug sapp Last week I ordered up a sheet of Viton to try. I'm sure I can easily make a cutter/stamp on the lathe. If they work I plan to make my own to use in my $13 overhaul kits. I do agree the life of the Chinese rubber disc seems to be short. In my opinion several factors are the prime movers in determining the life of the discs, one is the pressure you have you pop off valve set at. The Chinese set theirs at exactly 45 ATMS, while many US aircraft are set at 50 or higher. Second is the use of oils which may be attacking the rubber (making it softer). The Chinese use only castor oil. Third would be the stainless steel springs, rust particles and broken spring parts from the stock (std steel) Chinese often cause check valves not to seal properly. Doug On Thu, Jan 31, 2013 at 9:17 AM, Hank Gibson wrote: > > Can you all share the details of how the proper diameter disc is stamped > out; type of tool, etc? > > Thanks- Hoot > > Sent from my iPhone > > On Jan 31, 2013, at 11:36 AM, "Walter Lannon" wrote: > > > > > Elmar; > > > > I have been making them from 3/32" neoprene. They don't last forever > but at least a few years. Recently changed to VITON. We'll see how that > stands up. > > > > The material must be a nitrile, not natural, rubber of a fairly high > Durometer reading - about 70 as I recall. > > > > Walt > > > > -----Original Message----- From: Elmar & Manuela Hegenauer > > Sent: Wednesday, January 30, 2013 8:39 PM > > To: yak-list@matronics.com > > Subject: Yak-List: pneumatic system woes > > > samira.h@shaw.ca> > > > > Keith and others, > > > > I usually have my all my check valves > > on my CJ overhauled with every annual. > > > > For that purpose I have stocked up springs > > and rubber pads but I can't remember the > > supplier :-( > > > > To make a long story short, all those rubber > > pads I have used over the years have failed > > sooner or later between the annuals, so I > > got curious. > > > > Now let's get technical, Brian Lloyd are > > you still alive? > > > > The rubber pad in a CJ check valve has a > > nominal diameter of 13 mm what translates > > into a area of circle of roughly 132 square > > millimetres or 1.32 square centimetres. > > > > The physical weight introduced to this little > > piece of rubber is around 66kgs/145 lbs at > > 50 bars/700 psi. > > > > That is a lot of pressure on a small rubber disc > > going against the sharp and perforated > > seat of the lower check valve assembly. > > > > I have done some tests in my workshop at factor > > 1.5 over a period of several months and the rubber > > pads all disintegrated (with and without air tool oil), > > the material seems to be too thin and soft!!! > > > > Any constructive thoughts or ideas? > > > > cheers > > > > Elmar > > > > > > > > > > > > > > > > > > ________________________________ Message 6 _____________________________________ Time: 09:53:51 AM PST US From: "Tom Elliott" Subject: RE: Yak-List: pneumatic system woes The ones I bought from Gary Bunn have been holding up very well. I do not know what the material is? Some of them have been in place for 5 + years Tom Elliott CJ-6A NX63727 777 Quartz Ave PMB 7004 Sandy Valley NV 89019 Cell 541-297-5497 -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Walter Lannon Sent: Thursday, January 31, 2013 8:37 AM Subject: Re: Yak-List: pneumatic system woes Elmar; I have been making them from 3/32" neoprene. They don't last forever but at least a few years. Recently changed to VITON. We'll see how that stands up. The material must be a nitrile, not natural, rubber of a fairly high Durometer reading - about 70 as I recall. Walt -----Original Message----- From: Elmar & Manuela Hegenauer Sent: Wednesday, January 30, 2013 8:39 PM Subject: Yak-List: pneumatic system woes --> Keith and others, I usually have my all my check valves on my CJ overhauled with every annual. For that purpose I have stocked up springs and rubber pads but I can't remember the supplier :-( To make a long story short, all those rubber pads I have used over the years have failed sooner or later between the annuals, so I got curious. Now let's get technical, Brian Lloyd are you still alive? The rubber pad in a CJ check valve has a nominal diameter of 13 mm what translates into a area of circle of roughly 132 square millimetres or 1.32 square centimetres. The physical weight introduced to this little piece of rubber is around 66kgs/145 lbs at 50 bars/700 psi. That is a lot of pressure on a small rubber disc going against the sharp and perforated seat of the lower check valve assembly. I have done some tests in my workshop at factor 1.5 over a period of several months and the rubber pads all disintegrated (with and without air tool oil), the material seems to be too thin and soft!!! Any constructive thoughts or ideas? cheers Elmar much more: ________________________________ Message 7 _____________________________________ Time: 09:54:21 AM PST US From: "William Halverson" Subject: Re: Yak-List: pneumatic system woes Are check valves a problem for YAKs? William -----Original Message----- From: doug sapp [mailto:dougsappllc@gmail.com] Sent: Thursday, January 31, 2013 09:39 AM Subject: Re: Yak-List: pneumatic system woes Last week I ordered up a sheet of Viton to try. I'm sure I can easily make a cutter/stamp on the lathe. If they work I plan to make my own to use in my $13 overhaul kits. I do agree the life of the Chinese rubber disc seems to be short. In my opinion several factors are the prime movers in determining the life of the discs, one is the pressure you have you pop off valve set at. The Chinese set theirs at exactly 45 ATMS, while many US aircraft are set at 50 or higher. Second is the use of oils which may be attacking the rubber (making it softer). The Chinese use only castor oil. Third would be the stainless steel springs, rust particles and broken spring parts from the stock (std steel) Chinese often cause check valves not to seal properly. Doug On Thu, Jan 31, 2013 at 9:17 AM, Hank Gibson wrote: > > Can you all share the details of how the proper diameter disc is stamped > out; type of tool, etc? > > Thanks- Hoot > > Sent from my iPhone > > On Jan 31, 2013, at 11:36 AM, "Walter Lannon" wrote: > > > > > Elmar; > > > > I have been making them from 3/32" neoprene. They don't last forever > but at least a few years. Recently changed to VITON. We'll see how that > stands up. > > > > The material must be a nitrile, not natural, rubber of a fairly high > Durometer reading - about 70 as I recall. > > > > Walt > > > > -----Original Message----- From: Elmar & Manuela Hegenauer > > Sent: Wednesday, January 30, 2013 8:39 PM > > To: yak-list@matronics.com > > Subject: Yak-List: pneumatic system woes > > > samira.h@shaw.ca> > > > > Keith and others, > > > > I usually have my all my check valves > > on my CJ overhauled with every annual. > > > > For that purpose I have stocked up springs > > and rubber pads but I can't remember the > > supplier :-( > > > > To make a long story short, all those rubber > > pads I have used over the years have failed > > sooner or later between the annuals, so I > > got curious. > > > > Now let's get technical, Brian Lloyd are > > you still alive? > > > > The rubber pad in a CJ check valve has a > > nominal diameter of 13 mm what translates > > into a area of circle of roughly 132 square > > millimetres or 1.32 square centimetres. > > > > The physical weight introduced to this little > > piece of rubber is around 66kgs/145 lbs at > > 50 bars/700 psi. > > > > That is a lot of pressure on a small rubber disc > > going against the sharp and perforated > > seat of the lower check valve assembly. > > > > I have done some tests in my workshop at factor > > 1.5 over a period of several months and the rubber > > pads all disintegrated (with and without air tool oil), > > the material seems to be too thin and soft!!! > > > > Any constructive thoughts or ideas? > > > > cheers > > > > Elmar > > > > > > > > > > > > > > > > > > ________________________________ Message 8 _____________________________________ Time: 10:37:55 AM PST US From: "A. Dennis Savarese" Subject: Re: Yak-List: pneumatic system woes The check valves in the Yak 52 are totally different internally than the ones in the CJ. They also have a rubber seal on the end of a piston. The sealing surface does not a sharp edge. The rubber seal on the piston presses up against a smooth, rounded edge surface. Denni A. Dennis Savarese 334-285-6263 334-546-8182 (mobile) www.yak-52.com Skype - Yakguy1 On 1/31/2013 11:52 AM, William Halverson wrote: > > > Are check valves a problem for YAKs? > > William > > -----Original Message----- > From: doug sapp [mailto:dougsappllc@gmail.com] > Sent: Thursday, January 31, 2013 09:39 AM > To: yak-list@matronics.com > Subject: Re: Yak-List: pneumatic system woes > > Last week I ordered up a sheet of Viton to try. I'm sure I can easily make > a cutter/stamp on the lathe. If they work I plan to make my own to use in > my $13 overhaul kits. I do agree the life of the Chinese rubber disc seems > to be short. In my opinion several factors are the prime movers in > determining the life of the discs, one is the pressure you have you pop off > valve set at. The Chinese set theirs at exactly 45 ATMS, while many US > aircraft are set at 50 or higher. Second is the use of oils which may be > attacking the rubber (making it softer). The Chinese use only castor oil. > Third would be the stainless steel springs, rust particles and broken > spring parts from the stock (std steel) Chinese often cause check valves > not to seal properly. > > Doug > > On Thu, Jan 31, 2013 at 9:17 AM, Hank Gibson wrote: > >> >> Can you all share the details of how the proper diameter disc is stamped >> out; type of tool, etc? >> >> Thanks- Hoot >> >> Sent from my iPhone >> >> On Jan 31, 2013, at 11:36 AM, "Walter Lannon" wrote: >> >>> >>> Elmar; >>> >>> I have been making them from 3/32" neoprene. They don't last forever >> but at least a few years. Recently changed to VITON. We'll see how that >> stands up. >>> The material must be a nitrile, not natural, rubber of a fairly high >> Durometer reading - about 70 as I recall. >>> Walt >>> >>> -----Original Message----- From: Elmar & Manuela Hegenauer >>> Sent: Wednesday, January 30, 2013 8:39 PM >>> To: yak-list@matronics.com >>> Subject: Yak-List: pneumatic system woes >>> >> samira.h@shaw.ca> >>> Keith and others, >>> >>> I usually have my all my check valves >>> on my CJ overhauled with every annual. >>> >>> For that purpose I have stocked up springs >>> and rubber pads but I can't remember the >>> supplier :-( >>> >>> To make a long story short, all those rubber >>> pads I have used over the years have failed >>> sooner or later between the annuals, so I >>> got curious. >>> >>> Now let's get technical, Brian Lloyd are >>> you still alive? >>> >>> The rubber pad in a CJ check valve has a >>> nominal diameter of 13 mm what translates >>> into a area of circle of roughly 132 square >>> millimetres or 1.32 square centimetres. >>> >>> The physical weight introduced to this little >>> piece of rubber is around 66kgs/145 lbs at >>> 50 bars/700 psi. >>> >>> That is a lot of pressure on a small rubber disc >>> going against the sharp and perforated >>> seat of the lower check valve assembly. >>> >>> I have done some tests in my workshop at factor >>> 1.5 over a period of several months and the rubber >>> pads all disintegrated (with and without air tool oil), >>> the material seems to be too thin and soft!!! >>> >>> Any constructive thoughts or ideas? >>> >>> cheers >>> >>> Elmar >>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> > > ________________________________ Message 9 _____________________________________ Time: 10:48:14 AM PST US From: "A. Dennis Savarese" Subject: Re: Yak-List: pneumatic system woes I meant, "does not HAVE a sharp edge. Sorry. Dennis A. Dennis Savarese 334-285-6263 334-546-8182 (mobile) www.yak-52.com Skype - Yakguy1 On 1/31/2013 12:35 PM, A. Dennis Savarese wrote: > > > The check valves in the Yak 52 are totally different internally than > the ones in the CJ. They also have a rubber seal on the end of a > piston. The sealing surface does not a sharp edge. The rubber seal > on the piston presses up against a smooth, rounded edge surface. > Denni > > A. Dennis Savarese > 334-285-6263 > 334-546-8182 (mobile) > www.yak-52.com > Skype - Yakguy1 > > On 1/31/2013 11:52 AM, William Halverson wrote: >> >> >> >> Are check valves a problem for YAKs? >> >> William >> >> -----Original Message----- >> From: doug sapp [mailto:dougsappllc@gmail.com] >> Sent: Thursday, January 31, 2013 09:39 AM >> To: yak-list@matronics.com >> Subject: Re: Yak-List: pneumatic system woes >> >> Last week I ordered up a sheet of Viton to try. I'm sure I can easily >> make >> a cutter/stamp on the lathe. If they work I plan to make my own to >> use in >> my $13 overhaul kits. I do agree the life of the Chinese rubber disc >> seems >> to be short. In my opinion several factors are the prime movers in >> determining the life of the discs, one is the pressure you have you >> pop off >> valve set at. The Chinese set theirs at exactly 45 ATMS, while many US >> aircraft are set at 50 or higher. Second is the use of oils which >> may be >> attacking the rubber (making it softer). The Chinese use only castor >> oil. >> Third would be the stainless steel springs, rust particles and broken >> spring parts from the stock (std steel) Chinese often cause check valves >> not to seal properly. >> >> Doug >> >> On Thu, Jan 31, 2013 at 9:17 AM, Hank Gibson wrote: >> >>> >>> Can you all share the details of how the proper diameter disc is >>> stamped >>> out; type of tool, etc? >>> >>> Thanks- Hoot >>> >>> Sent from my iPhone >>> >>> On Jan 31, 2013, at 11:36 AM, "Walter Lannon" wrote: >>> >>>> >>>> Elmar; >>>> >>>> I have been making them from 3/32" neoprene. They don't last forever >>> but at least a few years. Recently changed to VITON. We'll see >>> how that >>> stands up. >>>> The material must be a nitrile, not natural, rubber of a fairly high >>> Durometer reading - about 70 as I recall. >>>> Walt >>>> >>>> -----Original Message----- From: Elmar & Manuela Hegenauer >>>> Sent: Wednesday, January 30, 2013 8:39 PM >>>> To: yak-list@matronics.com >>>> Subject: Yak-List: pneumatic system woes >>>> >>> samira.h@shaw.ca> >>>> Keith and others, >>>> >>>> I usually have my all my check valves >>>> on my CJ overhauled with every annual. >>>> >>>> For that purpose I have stocked up springs >>>> and rubber pads but I can't remember the >>>> supplier :-( >>>> >>>> To make a long story short, all those rubber >>>> pads I have used over the years have failed >>>> sooner or later between the annuals, so I >>>> got curious. >>>> >>>> Now let's get technical, Brian Lloyd are >>>> you still alive? >>>> >>>> The rubber pad in a CJ check valve has a >>>> nominal diameter of 13 mm what translates >>>> into a area of circle of roughly 132 square >>>> millimetres or 1.32 square centimetres. >>>> >>>> The physical weight introduced to this little >>>> piece of rubber is around 66kgs/145 lbs at >>>> 50 bars/700 psi. >>>> >>>> That is a lot of pressure on a small rubber disc >>>> going against the sharp and perforated >>>> seat of the lower check valve assembly. >>>> >>>> I have done some tests in my workshop at factor >>>> 1.5 over a period of several months and the rubber >>>> pads all disintegrated (with and without air tool oil), >>>> the material seems to be too thin and soft!!! >>>> >>>> Any constructive thoughts or ideas? >>>> >>>> cheers >>>> >>>> Elmar >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >> >> >> >> >> >> >> > > ________________________________ Message 10 ____________________________________ Time: 11:16:07 AM PST US From: "William Halverson" Subject: Re: Yak-List: pneumatic system woes OK thanks! -----Original Message----- From: A. Dennis Savarese [mailto:dsavarese0812@bellsouth.net] Sent: Thursday, January 31, 2013 10:35 AM Subject: Re: Yak-List: pneumatic system woes The check valves in the Yak 52 are totally different internally than the ones in the CJ. They also have a rubber seal on the end of a piston. The sealing surface does not a sharp edge. The rubber seal on the piston presses up against a smooth, rounded edge surface. Denni A. Dennis Savarese 334-285-6263 334-546-8182 (mobile) www.yak-52.com Skype - Yakguy1 On 1/31/2013 11:52 AM, William Halverson wrote: > > > Are check valves a problem for YAKs? > > William > > -----Original Message----- > From: doug sapp [mailto:dougsappllc@gmail.com] > Sent: Thursday, January 31, 2013 09:39 AM > To: yak-list@matronics.com > Subject: Re: Yak-List: pneumatic system woes > > Last week I ordered up a sheet of Viton to try. I'm sure I can easily make > a cutter/stamp on the lathe. If they work I plan to make my own to use in > my $13 overhaul kits. I do agree the life of the Chinese rubber disc seems > to be short. In my opinion several factors are the prime movers in > determining the life of the discs, one is the pressure you have you pop off > valve set at. The Chinese set theirs at exactly 45 ATMS, while many US > aircraft are set at 50 or higher. Second is the use of oils which may be > attacking the rubber (making it softer). The Chinese use only castor oil. > Third would be the stainless steel springs, rust particles and broken > spring parts from the stock (std steel) Chinese often cause check valves > not to seal properly. > > Doug > > On Thu, Jan 31, 2013 at 9:17 AM, Hank Gibson wrote: > >> >> Can you all share the details of how the proper diameter disc is stamped >> out; type of tool, etc? >> >> Thanks- Hoot >> >> Sent from my iPhone >> >> On Jan 31, 2013, at 11:36 AM, "Walter Lannon" wrote: >> >>> >>> Elmar; >>> >>> I have been making them from 3/32" neoprene. They don't last forever >> but at least a few years. Recently changed to VITON. We'll see how that >> stands up. >>> The material must be a nitrile, not natural, rubber of a fairly high >> Durometer reading - about 70 as I recall. >>> Walt >>> >>> -----Original Message----- From: Elmar & Manuela Hegenauer >>> Sent: Wednesday, January 30, 2013 8:39 PM >>> To: yak-list@matronics.com >>> Subject: Yak-List: pneumatic system woes >>> >> samira.h@shaw.ca> >>> Keith and others, >>> >>> I usually have my all my check valves >>> on my CJ overhauled with every annual. >>> >>> For that purpose I have stocked up springs >>> and rubber pads but I can't remember the >>> supplier :-( >>> >>> To make a long story short, all those rubber >>> pads I have used over the years have failed >>> sooner or later between the annuals, so I >>> got curious. >>> >>> Now let's get technical, Brian Lloyd are >>> you still alive? >>> >>> The rubber pad in a CJ check valve has a >>> nominal diameter of 13 mm what translates >>> into a area of circle of roughly 132 square >>> millimetres or 1.32 square centimetres. >>> >>> The physical weight introduced to this little >>> piece of rubber is around 66kgs/145 lbs at >>> 50 bars/700 psi. >>> >>> That is a lot of pressure on a small rubber disc >>> going against the sharp and perforated >>> seat of the lower check valve assembly. >>> >>> I have done some tests in my workshop at factor >>> 1.5 over a period of several months and the rubber >>> pads all disintegrated (with and without air tool oil), >>> the material seems to be too thin and soft!!! >>> >>> Any constructive thoughts or ideas? >>> >>> cheers >>> >>> Elmar >>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >> >> > > ________________________________ Message 11 ____________________________________ Time: 12:19:46 PM PST US From: Elmar & Manuela Hegenauer Subject: Yak-List: RE: pneumatic system woes Hi again, I would like to thank everybody for their input and possible solutions. I will follow the one or other advice and will do some tests again over a period of several months before I introduce the new material to my aircraft. Thank you again. cheers Elmar P.S.: Dennis is right, I have one YAK 52 check valve in my CJ and it works for 16 years without any problems. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message yak-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Yak-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/yak-list Browse Digests http://www.matronics.com/digest/yak-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.