Accuracy should trump easy-peasy

In January the ASME A112.14.3 sub-committee will once again meet to try to update the standard, which has remained unchanged since its publication in 2000.

One of the issues that the committee has struggled to come to consensus on is the incremental test cycles and the skim tank procedure.

At the risk of boring the reader to death - something I normally try to avoid - let me explain the procedure and the inherent problem that I believe needs to be addressed.

This is what the ASME A112.14.3 test apparatus looks like, conceptually anyway.

Once the flow rate is calibrated from the test sinks to the desired flow rate for the interceptor being tested, the testing procedure involves opening the drain valve on the test sinks and "let 'er rip".

The flow from the test sinks will pass through the grease interceptor and into the skim tank, after which any accumulated lard found in the skim tank is skimmed off (hence the clever and sophisticated name of the tank), dewatered and weighed. The weight of the lard taken from the skim tank is deducted from the weight of the lard introduced into the test sinks and the difference representing the efficiency of the interceptor during that specific test cycle.

Now, the skim tank is supposed to have a waste outlet connected to the bottom of the tank at one end and be trapped to retain approximately 18 inches of water in the tank. The tank is also provided with a four (4) inch bottom drain to permit draining and cleaning.

The purpose of the waste outlet being trapped to retain 18 inches of water in the tank is so that the tank volume does not drop below 18 inches during a test cycle.  In practice what this means is that the flow from the grease interceptor can actually pass through the skim tank during a test cycle since the waste outlet is typically not closed off during testing.

Is this a problem?

Perhaps not, but since the point of the testing procedure is to determine with the greatest accuracy possible the efficiency of a grease interceptor, this doesn't seem right to me.

In case you didn't quite follow all that, allow me to clarify the issue.

The skim tank is just that a tank intended to capture the effluent from the grease interceptor during a test run in order to measure the amount of lard that escaped the interceptor which will determine the efficiency of the interceptor.

If the tank is open during a test run it is possible for some of the lard that enters the skim tank to escape the skim tank.  Any lard which escapes the skim tank is automatically counted as lard that must be in the grease interceptor, which has the potential of reporting a higher than actual efficiency of the interceptor for a given test cycle.

Since the interceptor will be tested over a minimum of 13 cycles, the problem can be compounded resulting in a potentially significant higher than actual average efficiency for a certified grease interceptor.

The solution would seem to be a simple one; keep the skim tank closed during each test cycle.

I have proposed just such a radical idea to the committee before but have received resistance from some who cite the benefit of the "automatic" nature of the testing when the tank is allowed to remain open during each test cycle.

I take the term "automatic" to basically mean, "easy-peasy", which is actually short for "easy-peasy-lemon-squeezy", which means "very easy" and makes me think about vodka and a drink called a Lemon Drop...

I doubt that the proponent of the argument intended committee members to conjure up images of
alcoholic drinks, but I did anyway.

Further arguments have been proposed that at higher flows and a two-drop series (allowed by the standard) that a lack of  human intervention at the required time would cause the skim tank to overflow, invalidating the test.

It's hard to not respond with a bit of sarcasm to that argument, but I'll abstain and simply say, "hogwash".

The committee has already agreed to enlarge the size of the skim tank for testing grease interceptors at flow rates over 50 gpm.  The size of the larger skim tank will allow for two complete drops (test increments) at 100 gpm, which is 400 total gallons of water. There is no risk of overflowing the skim tank unless the "human interaction" fails to drain the skim tank prior to another test cycle.

If testing personnel fail to drain the skim tank down between two successive two-drop tests at 100 gpm, then I would agree that the test results would be invalid, requiring the interceptor to be tested over from the beginning - and the testing personnel fired for incompetence (after they clean up the mess, of course).

Anyways, it seems to me that accuracy in testing should be the most important issue - definitely more important that what's easy-peasy.

I'll update this post if any progress on the issue is made at the next committee meeting.

Trapping and Venting for Grease Interceptors

From time to time I will get an email that contains a schematic of a grease interceptor installation with the question, "does this look right?"

Usually the email-sender wants to know if the trapping and venting is shown correctly.

The answer requires a knowledge of both the applicable plumbing code and the installation requirements of the specific grease interceptor.

Model plumbing codes require each fixture discharging into a grease interceptor be individually trapped and vented, and require the installation of a vent downstream of the grease interceptor.

Standards also come into play when it comes to determining the type and location of vents upstream of a grease interceptor.

PDI G101 mandates the installation of an vented external flow control. The vent on the flow control is an air intake.  As the waste stream flows through the orifice in the flow control device negative pressure is created, drawing in air from the air intake which is intended to mix with the waste water as it enters the grease interceptor aiding in separation efficiency.

ASME A112.14.3 allows four types of ratings as follows:
  Type A - units with external flow control, with air intake (vent): directly connected
  Type B - units with external flow control, without air intake (vent): directly connected
  Type C - units without an external flow control: directly connected
  Type D - units without an external flow control: indirectly connected

Manufacturer's are required to identify which Type their interceptor is rated to when certifying to the ASME standard. 

PDI G101 and ASME A112.14.3 Type A certified interceptors are required to have a vented external flow control installed upstream of the interceptor.

Okay, so lets take a look at some drawings and see what works and what doesn't.

What's wrong with this installation?

It depends on which model plumbing code applies to the installation.

The International Plumbing Code (IPC) 1002.1 (exception 3) allows a grease interceptor to serve as a fixture trap - where it is intended by the manufacturer to serve as a trap - for a single fixture or a combination sink of not more than three compartments so long as the vertical distance from the outlet of the fixture to the inlet of the interceptor is not more than 30 inches and the developed length of the waste pipe from the most upstream fixture outlet to the inlet of the interceptor does not exceed 60 inches.

This drawing for a PDI G101/ASME Type A grease interceptor appears to be compliant with the IPC.  Assuming the interceptor is intended to serve as a fixture trap, there is no requirement to install an additional trap and vent between the fixture and the interceptor. 

The Uniform Plumbing Code (UPC) does not permit a grease interceptor to serve as a fixture trap and also prohibits the installation of a vent between the air intake on the flow control and the grease interceptor. The above diagram would not be compliant with the UPC. There needs to be a trap and vent between the fixture and the vented flow control fitting.

What's wrong with this installation?

Actually, nothing!

The drawing shows a PDI G101/ASME Type A grease interceptor connected to a the three compartment sink that is trapped and vented, an external flow control with air intake and a vent on the downstream side of the grease interceptor.

This installation would be compliant with both the IPC and the UPC.

What's wrong with this installation?

The drawing shows a PDI G101/ASME Type A grease interceptor with an external flow control with air intake, however it also shows a trap on the fixture but no vent for the trap.

This is not compliant with the IPC since the code does not allow double trapped fixtures. The code does allow the interceptor to serve as a trap - assuming that this interceptor is intended to serve as a fixture trap - thus adding a trap to the fixture upstream of the interceptor creates a double trapped fixture installation. Either adding a vent to the trap or removing the trap on the fixture altogether would solve the problem.

The only solution for compliance with the UPC is to add a vent for the trap on the fixture upstream of the vented flow control fitting.

What's wrong with this installation?

This drawing shows a semi-automatic draw-off type grease interceptor but without a vented external flow control.

Since all semi-automatic draw-off grease interceptors are certified to either PDI G101 or ASME A112.14.3 Type A (that I am aware of) an external vented flow control must be shown for compliance with the IPC.

For compliance with the UPC this drawing would have to show both a vented external flow control and a trap and vent for the fixture.

What's wrong with this installation?

Again, there is nothing wrong with this installation, though it may not be immediately obvious as to why.

The unit shown is certified to ASME A112.14.3 Type C (without external flow control) with a built-in or integral flow control and does not require an air intake.

That being the case the interceptor does not require a vented external flow control - jurisdictions unfamiliar with this type of interceptor often question drawings like this and understandably so.

This installation is compliant with both the IPC and the UPC since it shows a trapped and vented fixture discharging through an approved interceptor without external vented flow control with a vent installed downstream.

Air Admittance Valves (AAV)

The UPC does not include provisions for AAVs except as a part of an "Engineered Vent System" under section 912.0, much to the chagrin of engineers around the country. Many states that adopt or adapt the UPC have added an allowance for AAVs so you will have to check with your state to see if they are approved.

The IPC approves the use of and installation requirements for AAVs under section 918.0.

What's important to remember about AAVs is that they only allow for the relief of negative pressure in the drainage system. Therefore, when using an AAV to vent a grease interceptor, it's important that the drainage system has provision for the relief of positive pressure to ensure proper flow.

Boilerplate drawings can be trouble

To be honest, much of the confusion over whether a drawing shows a code compliant installation of a grease interceptor or not, can be the result of boilerplate drawings provided by manufacturers in submittals or installation instructions. Manufacturer's want to provide guidance for a broad range of installations without providing detailed drawings for every single installation variable that can exist. 

When it comes to traps and vents for grease interceptors and the fixtures discharging to them, it's incumbent upon an engineer or contractor to identify and comply with local code requirements regardless what a manufacturer's drawing shows. 

Hopefully after reading this post you will find it easier to identify a drawing that is right for your installation or one that needs to be corrected. 

Steel grease interceptor's costly but last tearout and replacement

Steel grease interceptor's corrode and fail over time.  That's a fact that's generally not in dispute.

How long it can take can vary of course,  but is influenced by restaurant menu, frequency of pumpouts and thoroughness of cleaning.

A corroding steel interceptor feeds FOG deposit formation in collection systems with lots of iron oxide, and when it fails it leaches it's contents and contaminates the surrounding soil.

The average life expectancy for a steel interceptor is roughly five years.

The cost to replace a failed steel interceptor runs in the thousands of dollars, which is why we put together a video; we wanted to show just what it takes to tearout and replace a corroded steel interceptor.

The best long term strategy to prevent the problems associated with failing steel interceptors, of course, is to mandate or approve only interceptors made with non-corrosive materials such as heavy duty thermoplastics or fiberglass. 

Eliminating steel interceptors will benefit all stakeholders including restaurant owners, wastewater authorities and the rest of us.

Check out the video here: https://vimeo.com/130551325

Regulatory compliance manager; fancy title or job description?

Recent activities I have been involved in have made me think that people really don't understand what it is that I do for a living.

There's no secret that I work for a grease interceptor manufacturer, But, what do I do for Schier?

Am I in sales?  No.

Wait, let me correct that.  I believe everyone is a sales person in one way or another.  For example, my wife would say that she is absolutely not cut out to be in sales.  But when she really wants something, she seems to have no problem presenting me with all of the features and benefits that would justify her request - which usually boil down to me having a happy and contented wife.

Hey, who doesn't want a happy and contented wife?

I generally find that preferable to just about anything else in the entire universe as it tends to provide a much "safer" environment at home.

My kids are some of the best sales people I know, with their mom and dad anyway.  They can be very creative in their justifications for why we should do this thing, or buy that thing, or go to such and such a place, all the while hammering home the features of this or that and the benefits that either they specifically would enjoy or that we all would collectively enjoy together.

Sales is really just the art of persuasion.  Some are naturally more gifted at it than others', and they typically end up selling for a living, but everyone has sold someone something at some point in their life.

Okay, so in the sense of doing "sales" for a living, no, I don't do that anymore. In other words, Schier does not pay me to sell anything.  I can't even tell you what our sales look like anymore because I am very much out of that loop.

So what do I do?

You might say that I am an advocate.

Merriam-Webster's dictionary defines advocate as, "one that defends or maintains a cause or proposal", or "one that supports or promotes the interests of another."

Who or what do I advocate for?

I am an advocate for fats, oils and grease (FOG) abatement in wastewater collection systems to reduce or eliminate sanitary sewer overflows (SSO) and their resultant risks to human health and safety.

That is my job description.  It has taken a while for it to come into clear focus, even for me.

What it means is that, while I am paid to do what I do by Schier Products, I am not paid to promote or sell for Schier Products.

I am in fact paid by Schier Products to advocate for what I think is right for FOG abatement in wastewater collection systems.

The advocacy I do is both internal and external to Schier.

When working with Schier I may advocate for some specific product improvements to make field inspections by pretreatment personnel easier or I might advocate for a new product to solve problems I am seeing in the field.

When working with pretreatment programs I may advocate for improving the requirements in an ordinance, or to remove some restrictive language that will hurt enforcement efforts, or to stop mandating products that are untested for performance.

When working with plumbing codes I may advocate for improved less-confusing-language regarding which fixtures should be routed to an interceptor, or I might take a stand against proposed changes that might lead to conflicts with pretreatment requirements or would loosen restrictions that would, in my opinion, be harmful to wastewater collection systems.

When working with standards such as ASME A112.14.3, I might advocate for more accountability in the standard and less prescriptive design requirements that shackle manufacturers and stifle innovation - something very much needed in grease interceptor design and operation, in my opinion.

I think it's important to understand that I see what I do, not as a job, but as a calling.

I believe in the "cause" of FOG abatement.

When you passionately believe in something you are willing to fight for it. You are willing to take actions that you believe in your heart will make a difference for your cause.

I guess that means that you might ruffle a few feathers. You might not "go along" to get along - if getting along means compromising what you believe in.

That being said, I love engaging with the pretreatment community and others who are equally interested in the issues surrounding FOG deposit formation and the exploration of solutions that might mitigate its deleterious effects.

My job title sure can be confusing, but I take my role in the cause seriously and I welcome the challenges, debates, and struggles that are necessary to make a real difference for us all.

The Inherent Problems with CSA B481.2

You may be familiar with Canadian Standards Association's (CSA) standard B481 which governs hydromechanical grease interceptors.

What you may not know is that B481 contains two alternative ratings designated as B481.1 and B481.2

All passive hydromechanical grease interceptors currently certified to CSA B481 are all listed to B481.1, which is basically the CSA version of ASME A112.14.3 and PDI G101.

By now you must be dying to know what B481.2 is, right?

By "dying to know" what I mean, of course, is that you have at least a mild curiosity if not a feigned interest; something more than an out right I-could-care-less feeling about the subject.

Hey, I'll take what I can get.

Anyway, assuming that you are in fact curious or at least feigning interest in the topic, lets take a look at this alternate rating and notice some inherent problems with it.

B481.2 uses effluent concentration sampling for testing the interceptor. The test requires the interceptor to be filled with water first, then have crushed granite added up to the interceptors maximum solids capacity (unless the interceptor is not designed to capture and contain solids), then  the interceptor is filled with sunflower oil to the point at which 5 test cycles of 12,000 mg/L will fill the interceptor to its rated capacity.

The interceptor is then tested 5 cycles with the oil mixture in the prescribed concentration and the interceptor’s effluent is sampled multiple times during the cycle. The average concentration of the oil in the effluent grab samples is recorded as the efficiency for the interceptor in mg/L.

Here are the problems with this rating:

Problem 1
5.3.3 Flow calibration - the standard does not specify any particular flow rates for testing, but instead, refers to B481.0 which specifies a range of flow rates with a lower limit of 7 gpm (26 L/m) and an upper limit of not more than 100 gpm (380 L/m). Thus a manufacturer can simply pick any flow rate for any interceptor and having tested to that flow rate, report the results of the effluent testing without regard to the flow rate at which the interceptor achieved the rating.

Here's the problem...

B481.0 requires the interceptor be marked with its flow rate according to either B481.1 or B481.2, but not both. Therefore a manufacturer can have an interceptor certified to B481.1 at 100 gpm (380 L/m) and can list that flow rate on its label but it doesn't have to list the flow rate used to achieve the effluent testing results under B481.2.

It's one or the other.

For example, let's say a manufacturer tests and certifies their interceptor to B481.1 at 100 gpm.  They can then list that flow rate on their label.  Now lets say they want to test to B481.2 and they discover that the interceptor's effluent concentration is 300 mg/L at 100 gpm. Now lets say they want to show 100 mg/L as their results but can only achieve that threshold at 20 gpm.

They can show the 100 mg/L test results, but are not required to label the interceptor with the lower flow rate used to achieve these test results.

How will anyone know that the interceptor didn't meet the effluent concentration at the flow rate listed on the label?


Problem 2
5.3.1 Solids preloading - B481.2 requires the interceptor to have solids (in the form of crushed granite) preloaded up to the interceptors maximum solids capacity unless the interceptor is not designed to capture and contain solids.

Here's the problem...

B481.2 does not provide a test protocol to determine a grease interceptors maximum solids capacity. 

Problem 3
5.3.4 Oil preloading - B481.2 requires the interceptor to have oil (in the form of sunflower oil) preloaded, according to section 6.2.3, based on the interceptors total rated oil storage capacity minus the amount of oil that will be added during testing.

Here's the problem...

B481.2 does not provide a test protocol to determine a grease interceptors total rated oil storage capacity.

Problem 4
The test protocol under B481.2 mandates that the water and the oil used to conduct the test be at room temperature. We would expect to find lower effluent concentration results from cooler temperature oil water mixtures owing to higher viscosity and flocculation which would be more resistant to mechanical sheering forces and turbulence inside the interceptor. This undermines the credibility of the test results as a predictor of real world installation performance.

Aside from these inherent problems there are two other issues to note:

1. No approved testing facility in North America has ever conducted the testing protocol under B481.2.

2. We are aware of only one jurisdiction in the US or Canada that actually requires compliance with B481.2. This apparent lack of jurisdictional support only serves to undermine the viability of this rating which dampens the incentive for manufacturers' to certify interceptors to this rating on their own.

As you can see there are a number of problems with certification to CSA B481.2 and these problems are serious enough that jurisdictions should avoid policy decisions that would include mandating compliance with this rating until these problems are adequately addressed in future amendments to the standard.