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MasterPlumbers
How does using (purple) primer improve solvent welded joints in PVC pipe?
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It cleans and softens the pipe so that the cement will adhere better. If it is not used, there is a good likelihood that in future years the joint will come apart.
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Again we see an example of a helper trying to play chemist. The cleaners and cements contain acetone or butanone, cyclohexane, and other non-polar solvents (depending on the brand used). They work by breaking some of the crosslinked PVC chains, thus weakening the overall integrity of the molecule. The solvents in the glues and cleaners are harsh on the lungs and nervous system, so try to work with plenty of ventillation.
The color is pretty much irrelevent, its just to add to the aesthetics to differentiate one brand from another. I’ve seen white, blue and colorless glues for PVC.
Your friendly chemist
Rich -
Richard:
He asked what it did, not how it did it. “Much knowledge doth make him mad”. -
Once there was a street vendor in London who walked around shouting, “Hot mutton pies, for sale”. A man bought one and after taking a bite, spit it out and ran after the vendor. He yelled at her, “It was not hot and it was not mutton.” Her reply was that that was what she called them, not what they were.
User names are like that. Maybe I should call myself The Mad LMP From the North Pole, or Little Kid with an I.Q. of 240. But any name used does not necessarily indicate who or what I am. I could just as easily call myself Sylvan LMP and no one would know if I was a homeless person on the streets who just happened to have a computer connection, and a good reference library to obtain information, or an actual LMP who just had an attitude. -
That was a total non-sequitor. Ie. it had nothing to do with anything. I seriously doubt your IQ is 240 since the Wechsler scale only goes to 210. Also, why would you be a tool bucket lugging helper that fetches coffee on occasion if you have that IQ? You wouldn’t, you’d be working under me in a lab, or be in medical school.
Words can be decieving, but only if they are used in such a manner.The friendly chemist
Rich
[Edited by Richard on 05 December 2000] -
By the way: The original question WAS: HOW do PVC glues and primers work? This requires an answer, not just a single sentence answer that doesn’t address anything.
The Friendly Chemist
Rich -
Guys, I really wanted to know how using primer improved the bond, if at all. I know the cement softens the PVC by breaking the bonds, etc, etc. That much said, what’s left for the primer to do that dosen’t get done by the solvent in the cement? Why can’t this be done with a “one-step” cement?
TIA
BTW, I can handle, and would be interested in, as much depth (or bredth) on this as you’ve got time to type. -
The Weld-On site has a great deal of information on the proper application of PVC primer and cement: http://www.ipscorp.com/wo_html/basic.html
While it does not get into the information Richard supplies, an email to them mught get the actual chemical reaction. Some useful info is:
“To make consistently good joints the following points should be clearly understood.
1. The joining surfaces must be softened and made semifluid.
2. Sufficient cement must be applied to fill gap between pipe and fitting.
3. Assembly of pipe and fittings must be made while the surfaces are still wet and cement is still fluid.
4. Joint strength develops as the cement dries. In the tight part of the joint, the surfaces will tend to fuse together, in the loose part, the cement will bond to both surfaces.
These areas must be softened and penetratedPenetration and softening can be achieved by the cement itself, by using a suitable primer or by the use of both primer and cement. For certain materials and in certain situations, it is necessary to use a primer. A suitable primer will usually penetrate and soften the surfaces more quickly than cement alone. Additionally, the use of a primer can provide a safety factor for the installer, for he can know under various temperature conditions when he has achieved sufficient softening. For example, in cold weather more time and additional applications may be required.”
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The primer also serves as a cleaner, so the cement can bond better to the pipe, and not the Schmutz on the pipe, which can cause a leak
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Richard your dealing with a HELPER and as all mechanics know half wit mentality only knows what they are told NOT concerning themselves as to WHY it works.( Never confuse a HELPER with facts as they get a headache)Helpers make GREAT ditch digger.
Richard your dealing with a HELPER and as all mechanics know half wit mentality only knows what they are told NOT concerning themselves as to WHY it works.
This is WHY I SAY AGAIN the Unions are no longer able to turn out QUALIFIED Journeymen.
They turn out kids who think the boss makes to much money and could careless as to WHY we have codes, Like Nazi’s a helper is just following orders Richard save your breath
This is WHY I SAY AGAIN the Unions are no longer able to turn out QUALIFIED Journeymen.
They turn out kids who think the boss makes to much money and could careless as to WHY we have codes, Like Nazi’s a helper is just following orders Richard save your breath. -
The color is pretty much irrelevent, its just to add to the aesthetics to differentiate one brand from another. I’ve seen white, blue and colorless glues for PVC.
Actually Rich some code officals like the colored glues so they can SEE that the joint was actually glued
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My thunder was stolen….
Different colors of primer to show inspector that yes indeed, it was primed before chemically welding. I have had 1 inspector tell me years ago that he wanted to see “AT LEAST” 3 inches of primer stain.
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Sylvan, I’m guessing that you were a brain-dead apprentice. I’m thankful that I apprenticed under individuals that had integrity. Not an arrogant bastard.
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I thought the purple primer was to splash all over the walls and finished surfaces.
Little drips of the stuff all over, that’s what tells me the plumbers helpers did the job and not the journeymen who don’t spill a drop of the stuff in the whole building.Respectfully David Walling
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Thanks All, for taking the time to help, with a special hats-off to Harold K. for the URL. I got what I was looking for on the primer and an eye opening, behind-the-scenes look of the “real” world of plumbers. Not a very civil bunch.
Sylvan, how DO you expect unions to turn out decent journeymen if every time an inquisitive mind asks a question they get *helped* by someone like you? Straighten up, and give a damn!
George Barrett PhD
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