Is Flex PVC safe to use?

[fritz]

I didn't want to sidetrack other threads where this is coming up so I thought I'd make a separate thread for it.

There has been debate as to weather or not it is a good idea to use PVC solvent to join flexible PVC to regular PVC. I heard from two trusted sources, a master plumber and a plumbing supply store with 50 years in the business, that Flexible PVC should only be used with barb fittings and should NEVER be attached with "glue".

This is in contrast to most information posted by DIYers on the internet. I don't believe I've ever seen a master plumber post a thread about his tank plumbing, maybe I have. Most of the stuff we see is done by people like us, that have tried stuff and it worked so we posted it. I've done many plumbing jobs on my tank, they all worked and I've posted them. I've had a few plumbers point out to me what I've done wrong and how it would fail due to my errors. After all I'm no plumber.

I found a link today from flexpvc.com
http://flexpvc.com/application-guidelines.shtml

Not that they are the be all end all of information on the subject, after all they recommend a thick glue, but they do state that it is in fact a hose and not PVC. They also don't mention it in a use whereby it would have to maintain any vertical pressure. This is what's scary is that in my uses and many that I see there is a good amount of gravity pulling on these joints.

Another scary thing is that according to their site, from a building perspective it is NOT sch 40 PVC but is classified as hose because water run through flex PVC will pick up a "plastic taste". This will not happen with SCH 40 PVC. Now if we can detect a plastic taste to water ran through flex PVC that means that something has come off the pipe into the water giving it that taste, or smell. I don't know that anyone has used this product long enough to know for sure what the effects are.

FWIW I've used flex pvc solved to regular pvc in the past and had no leaks. That isn't to say that I wouldn't ever have had it fail on me but while I ran it, 6 months or so, it was fine.

 

[Domboski]

I glued flexible PVC that connected by above tank fuge to my main display and it eventually sprung a leak. I also used ring clamps that at least kept the Flex PVC from completely disconnecting from the above tank fuge. It took about 2 years before it started leaking. I had no idea I couldn't glue flex PVC though.

That is the only place I have ever used Flex PVC so my experience is based only on one instance.

 

[ReefnQueens]

i definately wouldnt trust just using glue with flex pvc...no way , just like domboski said it will eventually leak , just get the right fittings and do it right the first time =)

 

[jhale]

three years, glued flex and pvc fittings, no problems.

my joints have little pressure on them. that may be helping.

fwiw when I glued the plumbing the flex did melt and bond to the pvc.
I tested the joint by trying to pull them apart, they were joined as quickly and as strongly as a regular pvc joint.

the question whether there is a problem with chemicals leaching from the flex is interesting.

 

[fritz]

Flexpvc.com answered my e-mail:

The flex pvc pipe we sell uses regular pvc couples, 90's, etc. Just regular fittings. Flex pvc is NOT designed to be used with barbs, and the manf. will void all warranties if used with barbs. (although people do it all the time, I'm sure.)

Note however, there are a lot of products people call "Flex pvc". Our website is trademark "Flex PVC" as a business AKA, but there are people who call any flexible plastic pipe or tubing as "flex or flexible pvc." As a matter of industry practice, if it's called pipe, it uses fittings. If it's called hose or tubing, it uses barbs. However, to make matters worse, our flexible pvc pipe is classified as hose by the standards committe because it does not fit the definition of pipe!

There website does state however that this FLex PVC is not Sch 40 PVC.

 

[meschaefer]

Interesting question, that I haven't seen addressed before.

My Flex PVC has only been running five months, so we will see. I have used it before, but not under any pressure, where this time it is under a lot of pressure.

That being said, there are many many tanks using flex pvc and I would think that this issue would have come up if it was a major problem. I know that when I was planning out my current tank, that I read through a lot of tank threads in the large tank forum on RC where a lot of flex is used and never once came across a problem or even mention that this could be a problem or concern.

I guess that it would make sense that you could have some problems, as the flex pvc has some give to it This might allow it to move in the joint more than solid PVC would, adding stress and causing the bond to loosen up.

 

[masterswimmer]

Fred, your second post conflicts your first post. Is the email you received correct? Or is the website you quoted correct?

We've been using Flex PVC for a long time and as Jon said, all is quiet on the western front.

swimmer

 

[jejton]

From your link:
While white FlexPVC does have an NSF rating, it is not suitable for potable (drinking) water applications. There is nothing toxic in the pipe, but it will pick up a "plastic taste" if water sits in it for several hours. This is the only reason it doesn't have a potable water rating: it can't pass the taste test. Same for black or gray. Neither can be used for potable drinking water.



I just want to make sure I understand what we're talking about - we're talking about the stuff thats often called Spaflex? If so, I dont see how you can use a hose barb to hold it.

There website does state however that this FLex PVC is not Sch 40 PVC.

When is "schedule 40" not schedule 40? Our flexible PVC is treated as a hose by the building industry, not a pipe. Thus our hose fits Schedule 40 fittings (dimensionally) and can be used in place of schedule 40 pipe for many applications, but it does not meet all the requirements for schedule 40 pipe. (If you look at the specification on the home page you'll see the pressure ratings are not the same as schedule 40 pipe.) So, while we call it "flexible pvc pipe" in reality it's a hose that fits perfectly into schedule 40 fittings, but it can't meet the most stringent "schedule 40 pipe" requirements.



Do I do anything differently when gluing flexible PVC Pipe?

One thing you do NOT do is twist the pipe once it's inserted into the fitting. Just push straight in, and hold. Be sure you get a good coating of glue 360 degrees around the pipe and inside the fitting socket. Larger sizes need to be held for longer than smaller sizes of pipe. Other than that, it's the same as rigid pvc pipe. What type of glue do I use?

All our flexible pvc pipe is glued using traditional PVC pipe cement and primer. We recommend medium to heavy bodied glue, clear or blue, and any standard primer. We do not recommend the gray glue. You can also use our organic, non-toxic, glue.

Instead of posting more clips, here's their FAQ -
http://flexpvc.com/faq.shtml

and they state that its safe for salt and fw fish tanks.

 

[Wes]

i use it on my tank, and whomever built my condo building used it on my HVAC plumbing. I never heard that you were not supposed to glue flexible pvc until you brought it up.

 

[fritz]

Well for certain Flex PVC is not for suitable for potable water, every website is in agreement on that. Other than that there isn't much agreement.

Russ, in my second post the italics are the response to my e-mail inquiry. I was just pointing out that their website clearly states their "Flex PVC" is not sch 40 PVC.

Below are quotes from their website:

NEVER to be used where there is a constant "dead head" pressure. ie, There should normally be a flow of fluid through the pipe. The pressure ratings given are for flowing pressure situations. Typical okay uses are: swimming pools, spas, hottubs, whirlpool bathtubs, irrigation (after the valve), ponds, drainage, conduit, suction applications, etc. As long as there is flow in the pipe you should be fine within the rated specifications.

While white FlexPVC does have an NSF rating, it is not suitable for potable (drinking) water applications. There is nothing toxic in the pipe, but it will pick up a "plastic taste" if water sits in it for several hours. This is the only reason it doesn't have a potable water rating: it can't pass the taste test. Same for black or gray. Neither can be used for potable drinking water.


When is "schedule 40" not schedule 40? Our flexible PVC is treated as a hose by the building industry, not a pipe. Thus our hose fits Schedule 40 fittings (dimensionally) and can be used in place of schedule 40 pipe for many applications, but it does not meet all the requirements for schedule 40 pipe. (If you look at the specification on the home page you'll see the pressure ratings are not the same as schedule 40 pipe.) So, while we call it "flexible pvc pipe" in reality it's a hose that fits perfectly into schedule 40 fittings, but it can't meet the most stringent "schedule 40 pipe" requirements.

For some additional reading
http://reefcentral.com/forums/showthread.php?s=&threadid=1305074&highlight=spa+flex

The consensus on RC is that primer ruins the joints when joining flex PVC to regular PVC.

 

[fritz]

It just sounds weird to me, like they are downplaying some things:
"but it can't meet the most stringent Schedule 40 Pipe Requirements"
What are those requirements?
One of them is that the water can't taste like what it was sitting in which happens with flex pvc. Where did the taste come from? They claim nothing leaches out of the flex pvc and that it's not harmful or a big deal. Still something from the plastic got in the water or it wouldn't taste like plastic.

If the government says it's not safe for me to drink why would I run my RO/DI water through it? It costs a decent amount of money to strip everything out of my tap water, to run it through pipe not suited for potable water sounds crazy.

 

[Tim]

I don`t know if this was covered but spaflex (flex pvc) need`s specific glue made for just for it....

 

[fritz]

That seems to be the consensus of the RC people and they say not to use any primer.

 

[Tim]

I believe you still have to use primer.Primer I believe starts the chemical reaction, cleans and make`s the area ready for the glue....

 

[jhale]

I used primer, it softens the pipe a bit, but it did not effect the holding power of the bond.

I think the only argument against using flex-pvc may be possible contaminants. However I've seen plenty of awesome tanks plumbed with it so I can't say there is any reason to worry about it.

 

[masterswimmer]

I used primer, it softens the pipe a bit, but it did not effect the holding power of the bond.

I think the only argument against using flex-pvc may be possible contaminants. However I've seen plenty of awesome tanks plumbed with it so I can't say there is any reason to worry about it.

Ditto

 

[ECFENCING]

I've seen a post on wetwebmedia (Bob Fenner's site?) that indicated he preferred rigid to flex but I can't remember the specific reason.

I too have had flexpvc, spaflex or whatever flavor or variation it's called on my tank with no ill effects.

I think savko.com recommends a different cement for flexpvc.

 

[jackson6745]

I glued flex PVC directly into the bulkheads of my sump for 2 years with no problems.

 

[fritz]

All of you have had problems, you just don't know what they were caused by.

I started this thread because different manufacturers list different ways to connect it. Maybe all of them are ok. Anecdotally, people have stated that using the purple primer first is bad. One manufacturer states that primer should not be used, another says it should, another says only hose barb should be used, the government says it's not safe to drink from.

 

[aaron23]

the government says it's not safe to drink from.

too many variables on this topic?