Acid Tank Outlet plumbed right or wrong

[Jr9882]

Was told by the Superintendent "Journeyman Plumber" that this drain line is plumbed wrong, that it travels more than 180 degrees and further that it makes an S-trap.

First off, I understand that a in order to be considered an S-trap, you must first have a P-trap, and that these S-trap scenarios mainly occur underneath lavatories, in older homes, with the stack vent traveling up through the floor, versus inside the wall.

In the picture below, the outlet side is traveling horizontal and only changing elevation 90 degrees, then, reverting back 90 degrees, continuing horizontal into the combination.

He made us cut it out and place a wye downstream, with a 45 and rolling the 90.

He stated the Inspector would have failed the visual inspection and to save face, just go ahead and replace with a new design and flow pattern.

Call me out or give your thoughts, I am here to learn.



Jr
3rd yr Apprentice

 

[Terry]

He gave you good advice. Always reduce the changes of direction.

 

[Sponsor]

 

[James Henry]

1/4 bend + 1/4 bend = 180 degrees. I would have used an 1/8th bend and rolled the combo up at at a 45 degree angle but I can't be sure it would work, I would have to be there.

 

[Terry]

Wye and a 90 works well.

 

[Reach4]

What does this "acid tank" do, and why does it not need a trap? Is that a neutralizer for a tankless water heater or high efficiency furnace?

Was there a trap on the input?

 

[Terry]

I have never installed an acid tank before.
Let's see what's out there.

A post on this forum from 2006

I have been charged with solving a odor problem in a laboratory. A variety of plumbing fixtures are upstream of an acid neutralizing tank. The Canadian Plumbing Code mandates that neutralizing tanks must discharge to the sanitary system through a trap:

"Where a fixture or equipment discharges corrosive or acid waste, it shall dischage into a neutralizing or dilution tank that is connected to the sanitary drainage system through: a) a trap or b) an indirect connection"
(National Plumbing Code of Canada (2006), 2.4.4.4)

The plumbing inspector demanded that none of the fixtures upstream of the neutralizing tank be trapped, as that would consitute a double trapped condition. Therefore, some laboratory sinks and some floor drains are untrapped. The problem arises when bulk lab waste is disposed through the laboratory sinks. Offensive odour wafts up through the adjacent floor drains, and generates complaints.

Has this situation been encountered before? I've heard of a rubber "backflow" type insert that can prevent odour, but that seems like a bit of a mickey mouse solution which treats the symptom and not the problem. I believe the problem to be improper venting of the neutralizing tank itself.

Hi Bob, thanks for the response. The plumbing inspector regards the neutralizing tank itself as a trap. As all acid waste fixtures are upstream of (and drain through) the neutralizing tank, the inspector deemed that they are upstream of a trap, and therefore cannot be themselves trapped. I am also of the opinion that the inspector was incorrect, however regardless of previous code interpretations, the system has been installed, and has been buried under slab and framed into walls, and the space is occupied.

The meat of my question is whether there is a minimally invasive solution to this odour issue. We are considering capping all floor drains with cleanout fittings to prevent odour from escaping the system. The floor drains serve as "emergency" fittings only, in case of catastrophic equipment failure.This to me is a mickey mouse solution, but it does avoid the cost of cutting into epoxy flooring, and then cutting through the slab to install traps.

https://terrylove.com/forums/index.php?members/r551n.8736/

The entire thread here.

https://terrylove.com/forums/index.php?threads/odour-from-acid-drainage-system.9112/

 

[Sylvan]

All the acid wastes I ever installed we used Duriron or Pyrex for chemical waste

The acid crock is the trap . The Duriron was caulked using lead and special type of Oakum

Very expensive fittings and piping

 

[Jr9882]

What does this "acid tank" do, and why does it not need a trap? Is that a neutralizer for a tankless water heater or high efficiency furnace?

Was there a trap on the input?

That tank catches a trench drain, the trench drain has a cpvc trap and arm, as it is being utilized to catch any battery charging liquids from forklift storage and charging.

 

[Jeff H Young]

first off where is your long sweep 90 after the combi? I think you got a medium
Your Superintendent is slightly off track I think... Not quite an s trap. I might even call it an s trap. but an offset trap arm is a better call . pretty much the same concept .
Is any of this vented because it looks like I'm seeing horizontal wet venting. Engineered plans or some other code .
Keep After it JR9882 ! Its a great Trade If your supposed to put that together with no help I think that's journeyman . hope you get answers but I don't see that unvented trap arm as legal even without the 90s. Did you design the entire system ? no detailed plan?

 

[Jeff H Young]

BTW Superintendent is totally wrong rolling up a wye is still building the same s trap scenario that he told you about . because a trap arm must remain flat with grade. then there are still code issues ? with where is the vent serving the trap?

 

[Jr9882]

No specific DWV or SS plans describing the specific fittings needed and our company doesn't order excessive fittings, we sort of make a take-off list and vision our own route or path.

So the acid tank to the right in the picture has a 2" vented line to vent the tank itself, and upstream of that combination is a stack vent that serves an eye wash drain station and vents up with a 4" test above finished floor and reduces as a 3" vent thereafter.

So how we corrected the in question drain line was to remove the 1/4 bends and combo, then place a Wye rolled at a 45 downstream, connected to another 45 running to a 1/4 bend coming out of the tank, basically running parallel to main line and drop down with a 45 into the Wye.

I still dont grasp the 180 degree theory or if its a code, because I still picture 180 degrees of travel, as 90 down and 90 back towards the original direction of travel, thus, reversing the flow and stopping any drainage momentum.

 

[Jeff H Young]

JR9882, I thought there was a ptrap and those 2 90s represented a trap arm? otherwise where the heck could anyone be calling an s trap?
If there is a ptrap then You cant offset the trap arm , a basic principle. those 2 90s are a no no. but its not the degrees that has anything to do with it. at least that's the way I see it.