# Trap Primer with Air Gap



## plumbeng.

Ok so I have a question regarding trap primers. I have gotten a comment from a plans reviewer stating he would like a trap primer with an air gap and not directly connected to the p-trap of the floor drain. I have not really ever run into this in the 6 years I've been designing plumbing systems, so if anyone could direct me to a website with a cutsheet that would be great. Thanks in advance.

-Brian Mc.


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## SlickRick

I've been at it for almost 40 years and I have never heard of this. Approved trap primers are anti-siphon by design. I was a plumbing inspector at one time, could you post a copy of the detail you submitted?


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## plbgbiz

Ask the plumber on the job. He knows the answer.


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## easttexasplumb

The trap primer has a built in air gap.


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## plumbeng.

I believe he is asking to have some sort of gap between the sanitary system and the domestic water system. technically with a trap primer being directly connected to the p-trap of the floor drain, he says, there is a chance that things can back up and get into the domestic water system. He is calling for an RPZ, Reduced Pressure Zone, assembly on the water line supplying water to the trap primer to make sure the domestic water line isn't contaminated, the RPZ has a check valve that will not allow water to back up into the main water distribution piping.


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## SlickRick

plumbeng. said:


> I believe he is asking to have some sort of gap between the sanitary system and the domestic water system. technically with a trap primer being directly connected to the p-trap of the floor drain, he says, there is a chance that things can back up and get into the domestic water system. He is calling for an RPZ, Reduced Pressure Zone, assembly on the water line supplying water to the trap primer to make sure the domestic water line isn't contaminated.


They are anti-siphon, code approved without additional BF protection required. Is this actually Dallas or one of the suburbs? If he is wanting a BFP on each trap primer, that is just crazy.


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## SlickRick

Talk to me, I have things to do.


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## texplumber

Why not spec trap guards. Trap primers always seem to fail. Had one flood a building when the guts blew out of it.


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## SlickRick

or propose using deep seal "P" traps instead of trap primers.

IPC 1002.4 Trap seals


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## plumbeng.

I have sent him the cut sheet for the TP300 that has an air-gap feature. Hopefully this works. I forgot who suggested this, but Thank you for your help as well as everyone elses. If the examiner comes back with additional comments I will update this post. Thanks again for everyone's quick responses. I look forward to receiving and hopefully giving out advice in the future.


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## rjbphd

,veggie oil and be done with it


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## Widdershins

plumbeng. said:


> I believe he is asking to have some sort of gap between the sanitary system and the domestic water system. technically with a trap primer being directly connected to the p-trap of the floor drain, he says, there is a chance that things can back up and get into the domestic water system. He is calling for an RPZ, Reduced Pressure Zone, assembly on the water line supplying water to the trap primer to make sure the domestic water line isn't contaminated, the RPZ has a check valve that will not allow water to back up into the main water distribution piping.


Sounds like he's good friends with a backflow tester or he has a BATT license himself and tests 'em on the side.


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## justme

easttexasplumb said:


> The trap primer has a built in air gap.


there is not an air gap on a trap primer , you must mean an air break. Unless you can run your hand completely between the device and drain it is not an air gap.


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## plbgbiz

justme said:


> there is not an air gap on a trap primer , you must mean an air break. Unless you can run your hand completely between the device and drain it is not an air gap.


Yes there is.


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## johnlewismcleod

justme said:


> there is not an air gap on a trap primer , you must mean an air break. Unless you can run your hand completely between the device and drain it is not an air gap.


That's what the drilled hole is all about.

One of these days I'll figure out how to make a video and show you fellows how I make passive trap primers. They are fully air gapped as well.


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## justme

plbgbiz said:


> Yes there is.


No there is not an airgap on a trap primer it is an airbreak.If you can not run an object completely between the tail piece and the drain receptor it is not an air gap.The pic below no matter how many people call the hole in the pic an airgap it doesn't make it so.


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## plbgbiz

justme said:


> No there is not an airgap on a trap primer it is an airbreak.If you can not run an object completely between the tail piece and the drain receptor it is not an air gap.The pic below no matter how many people call the hole in the pic an airgap it doesn't make it so.


No offense Justme but I believe you are mistaken. 

There are more than one brand of trap primers that are manufactured in accordance with the ANSI/ASME A112.1.2 Air Gap in Plumbing Systems standard. 

Being able to pass an abject through clear space between the discharge pipe and the receptor is not part of the ANSI/ASME requirement. If that were the case, all air gap fittings connected to the bottom of RPZ units would be code violations.

The "pass through" standard may well be a local inspector's or municipality's pet peeve but it is not a requirement of the ANSI/ASME standard.


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## justme

plbgbiz said:


> No offense Justme but I believe you are mistaken.
> 
> There are more than one brand of trap primers that are manufactured in accordance with the ANSI/ASME A112.1.2 Air Gap in Plumbing Systems standard.
> 
> Being able to pass an abject through clear space between the discharge pipe and the receptor is not part of the ANSI/ASME requirement. If that were the case, all air gap fittings connected to the bottom of RPZ units would be code violations.
> 
> The "pass through" standard may well be a local inspector's or municipality's pet peeve but it is not a requirement of the ANSI/ASME standard.



But it is the USC standards , the guys who write the BOOK on backflow.

An Air Gap is a physical separation of the supply pipe by at least two pipe diameters (never less than one inch) vertically above the overflow rim of the receiving vessel. In this case line pressure is lost. Therefore, a booster pump is usually needed downstream, unless the flow of the water by gravity is sufficient for the water use. With an air gap there is no direct connection between the supply main and the equipment. An air gap may be used to protect against a contaminant or a pollutant, and will protect against both backsiphonage and backpressure. An air gap is the only acceptable means of protecting against lethal hazards.


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## plbgbiz

justme said:


> But it is the USC standards , the guys who write the BOOK on backflow.


I guess it depends on the inspectors. Here, ANSI/ASME trumps all.


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## SlickRick

Most trap primers have built in vacuum breakers.

Requiring additional BFP on a trap primer, would be like saying a ballcock needed a RPZ to back up an approved device.


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## justme

SlickRick said:


> Most trap primers have built in vacuum breakers.
> 
> Requiring additional BFP on a trap primer, would be like saying a ballcock needed a RPZ to back up an approved device.


Totally agree with you on it not needing any backflow device as long as it has the air gap. I would be curious to know what city or inspector is telling him this .


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## plbgbiz

Acccording to the USC interpretation, would this not be an approved air gap?


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## SlickRick

yes it would. 2x the pipe diameter or min. of 1"


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## plbgbiz

Right, but my confusion is related to not being able to pass something through the space between the fittings. 

So if the attachment on the RPZ passes, why would they have a problem with a similar setup on a primer?


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## SlickRick

plbgbiz said:


> Right, but my confusion is related to not being able to pass something through the space between the fittings.
> 
> So if the attachment on the RPZ passes, why would they have a problem with a similar setup on a primer?


Never heard of that, I would have to see it in writing.


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## justme

plbgbiz said:


> Acccording to the USC interpretation, would this not be an approved air gap?


A true airgap for the rpz would come into play where you terminate the drain line into the drain receptor.


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## SlickRick

justme said:


> A true airgap for the rpz would come into play where you terminate the drain line into the drain receptor.


How do you figure a airgap fitting is not a true airgap?


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## justme

SlickRick said:


> How do you figure a airgap fitting is not a true airgap?


The way it was explained in class for the TCEQ backflow license was that if you can't take a 1" wide yard stick or your hand and move it between the drain and drain receptor from all sides it is not an air gap . It would be considered an air break.The class was based on the USC 10th edition.


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## SlickRick

IPC Definitions, Air Gap , the unobstructed vertical distance through the free atmosphere between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture or other device and the flood level rim of the receptacle.

An air gap fitting has an unobstructed vertical path for discharge.


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## Titan Plumbing

It has to do with the two supports or arms that hold the receptor to the bottom of the RPZ, technically USC sees the arms as being able to allow contaminated water to make it's way back up into the RPZ.

I know it's a stretch, but it's how they see it. The pic Justme shows is what USC considers a the only true airgap.


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## SlickRick

justme said:


> The way it was explained in class for the TCEQ backflow license was that if you can't take a 1" wide yard stick or your hand and move it between the drain and drain receptor from all sides it is not an air gap . It would be considered an air break.


Where would the 1" wide yard stick come into play? Lets say it was a larger line that required a 4" AG.?

Air break, a piping arrangement in which a drain from a fixture, appliance or device discharges indirectly into another fixture, receptacle or interceptor at a point BELOW the flood level rim.


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## justme

SlickRick said:


> Where would the 1" wide yard stick come into play? Lets say it was a larger line that required a 4" AG. Air Breaks only apply to drainage.


Because of the way the code is written it says 2 x pipe size or 1" minimum.


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## justme

Titan Plumbing said:


> It has to do with the two supports or arms that hold the receptor to the bottom of the RPZ, technically USC sees the arms as being able to allow contaminated water to make it's way back up into the RPZ.
> 
> I know it's a stretch, but it's how they see it. The pic Justme shows is what USC considers a the only true airgap.



Technically its the bacteria and germs from the drain they are worried about.


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## plbgbiz

justme said:


> ....An Air Gap is a physical separation of the supply pipe by at least two pipe diameters (never less than one inch) vertically above the overflow rim of the receiving vessel.....


This definition of air gap does not preclude the physical connection of the discharge to the receptor. It only mandates a certain amount of free space which can easily be accomodated with the fittings still connected. If that free space is applied, contaminated water cannot get to the discharge. 

Is it possible that the instructor was just using the "yard stick" to illustrate the difference between a gap vs. break?


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## justme

plbgbiz said:


> This definition of air gap does not preclude the physical connection of the discharge to the receptor. It only mandates a certain amount of free space which can easily be accomodated with the fittings still connected. If that free space is applied, contaminated water cannot get to the discharge.
> 
> Is it possible that the instructor was just using the "yard stick" to illustrate the difference between a gap vs. break?


One other way I could explain it would be to use a kitchen faucet and sink as an example. the physical unobstructed vertical space between the water outlet and flood rim level of the fixture. Like titan said the 2 support arms keep it from being an unobstructed vertical space.Here in most municipalities we have to also provide a true airgap where the rpz drain terminates at the drain fixture.


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## SlickRick

So all the manufactures are unable to sell RPZ's where a AG fitting is needed except Apollo. And theirs is still connected so bacterial creep could POSSIBLY still occur. Someone at USCFCCCHR needs to find something else to do. So now all Air gap fittings except Apollo are not approved?


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## SlickRick

justme said:


> One other way I could explain it would be to use a kitchen faucet and sink as an example. the physical unobstructed vertical space between the water outlet and flood rim level of the fixture. Like titan said the 2 support arms keep it from being an unobstructed vertical space.Here in most municipalities we have to also provide a true airgap where the rpz drain terminates at the drain fixture.


How do the vert, arms obstruct the flow?


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## Widdershins

SlickRick said:


> How do the vert, arms obstruct the flow?


It isn't the obstruction to flow.

It's the land bridge to a bacterial/viral invasion.

Everybody is so hung up on actual liquid cross contamination.

Them lil' bacterial and viral fuquers can climb. And they do.


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## SlickRick

Widdershins said:


> It isn't the obstruction to flow.
> 
> It's the land bridge to a bacterial/viral invasion.
> 
> Everybody is so hung up on actual liquid cross contamination.
> 
> Them lil' bacterial and viral fuquers can climb. And they do.


So all the thousands of AG fittings need to be removed? bacterial creep is nothing new.


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## Widdershins

SlickRick said:


> So all the thousands of AG fittings need to be removed? bacterial creep is nothing new.


But suddenly more folks are aware of it.

A healthy immune system will beat back most of the nasties.

I'm not bovvered.


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## plbgbiz

Who or what is USC? Never heard of them. 

Do they have authority to supersede ASTM/ASME approvals?


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## SlickRick

University of Southern California foundation for cross-connection control and hydraulic research.

And no they don't.


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## justme

plbgbiz said:


> Who or what is USC? Never heard of them.
> 
> Do they have authority to supersede ASTM/ASME approvals?



astm only grades the material


http://www.usc.edu/dept/fccchr/

University of Southern California has pretty much wrote the book on Backflow prevention which has been accepted by a lot of states implementing backflow programs.


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## justme

SlickRick said:


> So all the thousands of AG fittings need to be removed? bacterial creep is nothing new.


Nothing needs to changed ,just provide a proper airgap at the rpz drain line termination.


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## Titan Plumbing

Justme, do you know of a Municipality that does not allow the air-gap fittings from Watts, etc?

Seems like I installed an RPZ where they did not allow the fitting and made me put a hub with a physical air gap.


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## justme

Titan Plumbing said:


> Justme, do you know of a Municipality that does not allow the air-gap fittings from Watts, etc?
> 
> Seems like I installed an RPZ where they did not allow the fitting and made me put a hub with a physical air gap.


I have heard some of our guys complain about one down in south Texas that wants a total airgap and makes you run a 4" indirect drain . But I have never my self ran across that . Around here as long as you put the air gap between the floor sink or hub drain you are good.One example ,the city of Plano has the water department enforce code for all backflow devices . The plumbing inspector has nothing to do with it when it comes to installation standards. I had to put Rpz's on dang mopsink because the store wouldn't quit putting a Y branch shutoff on the mopsink faucet with built in vacuum breaker,the city of Plano said OK,you have to put Rpz's on the water lines feeding the mopsink .So 1200. dollars later they have 2 more rpz's they have to test every year. Personally I think some of it is getting down right silly ,but what can you do.


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## SlickRick

To clarify RPZ's and Air gap fittings. The relief valve opening on a RPZ that requires an AG fitting to be attached to carry the clear water discharge via piping to and indirect waste receptor of design to control splashing when discharging into a sanitary waste system ( IPC 801.1) the termination of the drain line would be made via AG to the receptor. The fitting is an AG, but by code the discharge line must terminate into an indirect waste receptor, I assumed every plumber would know not to tie the discharge line directly into the waste system.


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## plbgbiz

SlickRick said:


> To clarify RPZ's and Air gap fittings. The relief valve opening on a RPZ that requires an AG fitting to be attached to carry the clear water discharge via piping to and indirect waste receptor of design to control splashing when discharging into a sanitary waste system ( IPC 801.1) the termination of the drain line would be made via AG to the receptor. The fitting is an AG, but by code the discharge line must terminate into an indirect waste receptor, I assumed every plumber would know not to tie the discharge line directly into the waste system.


The RPZ in the pic discharges to mop sink with an air break and picks up a water heater safety pan on the way. Inspector approved based on the code approved "air gap" fitting at the RPZ. 

My understanding from our local inspectors is that flow through trap primers with integral "air gaps" are approved for installation here without an additional free space air gap since they have received ASTM & ASME certification.

On the other hand if I am mistaken, it wouldn't be the first time.


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## BROOKLYN\PLUMB

plbgbiz said:


> The RPZ in the pic discharges to mop sink with an air break and picks up a water heater safety pan on the way. Inspector approved based on the code approved "air gap" fitting at the RPZ.
> 
> My understanding from our local inspectors is that flow through trap primers with integral "air gaps" are approved for installation here without an additional free space air gap since they have received ASTM & ASME certification.
> 
> On the other hand if I am mistaken, it wouldn't be the first time.


That used to be the case here but for a while now they want both, which I never understood cause one will prevent backflow (the one at the rpz because they are worried about flood line height)


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## SlickRick

BROOKLYN\PLUMB said:


> That used to be the case here but for a while now they want both, which I never understood cause one will prevent backflow (the one at the rpz because they are worried about flood line height)


Actually by code, it would require both and the AG at the indirect waste would prevent the bacterial creep.


NYC spells theirs out.


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## Airgap

My ears are burnin'


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## plbgbiz

Airgap said:


> My ears are burnin'


This thread must hold the record for most mentions of a single member. :laughing:


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## PLUMBER_BILL

*A little more on trap primers*

I had a township inspector request a pressure trap primer. {To keep a relief valve trap on a vent line primed 14' in the air} OK I inquired at a local house they never heard of an item like that. But if any body had them a specialty house in NJ would have them. I called the man who answered the phone said after he heard what I wanted. "Did you dig the 6 foot square hole outside"? I said what? "Well he said to use a pressure trap pirmer that hole must be there. That way when you call for a inspection show the hole to the inspector, when he looks in kick him so he falls. Then cover up the hole, thats how to get rid of A-Hole inspectors!


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