The Design/Build Conundrum, October 2011
I am an old guy that did not start out on DB but have worked in or with it (back in the 1970s) several times over the years. I never liked it because there is no good check and balance with this type of work. To me letting the contractor be in charge of the design is like asking a fox to watch over the hen house. To me I have never seen a DB come out to the client’s advantage; they end up on the loosing side. I used to feel bad about this but then I realize they deserved it by choosing to go that way. The last one I worked on was a new dorm at a university in Fairfax, VA. The client (not part of the university) tried to manage the project using architects from on company and engineers from another company; then hiring their own construction manager to make the project work. Luckily I keep very good notes and documented my meeting and conversations and published them. When it was over the owner tried to figure out why they did not get what they wanted plus the cost over run. Each time it came back to the company that I worked for I was able to pull out where I advised the client’s project manager where things were not being constructed properly; by way of punch list, field notes,etc. (the PM had left the project just before the end of the project). The sad thing was the PM never once answered the comments on the punch list. Somewhere along the way design firms have let the contractor sell a bill of goods to clients of how they will save them money by going DB when all I ever see is that contractor comes away with a pocket full of money and the client has a substandard building and systems. One item in particular was the construction of the HVAC rooms for each apartment. The architect made them so small that we could only find one manufacturer who had equipment that would fit. The architects were notified that the rooms were too small but they did not make any changes. The PM let the mechanical contractor purchase something that was cheaper but was too big for the rooms. I turned down the submittal but the PM let them go ahead because it saved money. After the PM had left and the client brought in their final inspection team they started asking my how the equipment would be serviced because the ends of the coils were jammed against the walls with no access. I advised them that they would have to cut a hole in the wall to perform any maintenance. Of course they were upset with me and then I produced the correspondence that was issued over many months that was unanswered.
Just thought I would share some of my experience with DB. John Mullis
July/August Peer to Peer
Thanks, Haig, for putting into words what a lot of us old timers have been trying to get across for years. Sometimes I find the old timers don’t know this approach either. The question is how do we get the new “blood”, or in the south the “youngins”, and uninformed old timers to read your article and apply it. All design folks, designers and engineers, need to stop and put themselves in the position of the contractor that has not been in on the project before and is seeing it for the first time. Have you put sufficient information into the design for the contractor to bid and build?
John Mullis
50+ years of design
July/August Peer to Peer
The article "Drawings or Specifications" in the July/August 2011 edition of Plumbing Systems & Design reflects a misunderstanding of typical construction contracts. The author's Guideline 4 is in error when it advises to, "Include a general note on the drawings stating which one will be the prevailing factor in the case of discrepancies between drawings and specifications" and that this is in accordance with American Institute of Architects recommendations.
On the contrary, AIA Document A201-2007 - General Conditions of the Contract for Construction, Paragraph 1.2.1 states, "The Contract Documents are complementary, and what is required by one shall be as binding as if required by all...". Paragraph 3.2.2 states, "...Contractor shall promply report to the Architect any errors, inconsistencies or omissions discovered..." Then, according to Paragraph 3.2.4, "...if the Contractor believes that additional cost or time is involved because of clarifications or instructions the Architect issues in response to the Contractor's notices or requests for information...Contractor shall make Claims..." as provided for elsewhere in AIA A201. Proforma preference for either drawings or specifications is insufficient.
Perhaps errors like this could be avoided if the article, "Tips on Starting Out", in the same issue, also advised young designers to observe two additional Basic Design Steps:
1. Read and understand the Conditions of the Construction Contract that the building Owner intends to use on the project, and
2. Make sure the plumbing drawings are coordinated with the plumbing specification sections.
I encourage plumbing designers seeking a better understanding of the relationships between drawings, specifications, conditions of the contract, and other contract documents to contact their local chapter of the Construction Specifications Institute (CSI). CSI offers a variety of educational programs on these topics, and a Construction Document Technologist (CDT) certificate to individuals that demonstrate an understanding of construction communications. Information is available at www.csinet.org.
Cordially, Michael Chusid, RA FCSI CCS
Help with Designations
I enjoy reading each issue of PS&D but have a problem with some of the post-nominal listed behind some of people's names. There have gotten to be so many that I have lost track of what they mean.
The following were in the May 2011 issue I do not know what some of them mean.
- LEED AP
- FASPE
- CFEI
- CPD
- CET
- PE
- SET
Would it be possible for ASPE to publish a list of these post-nominal and others as they pop up?
Thanks for your help, John Mullis - NLAMN*
*No Letters After My Name
- LEED AP = Leadership in Energy and Environmental Design Accredited Professional
- FASPE = ASPE Fellow
- CFEI = Certified Fire and Explosion Investigator
- CPD = Certified in Plumbing Design
- CET = Certified Engineering Technician
- PE = Professional Engineer
- SET = Senior Engineering Technician
June 2011 Plumbing 101 Column
I would like to point out some issues with the article, “Understanding two Variations of Manning's Formula”, appearing in Plumbing Systems & Design, June 2011.
- The Hydraulic radius equals D/4 (Diameter/4) ONLY when the depth of flow (d) equals the Diameter, d=D, (full flow) or half the Diameter (d=D/2)
- You should investigate the claim that Hydraulic radius is “also called the mean depth of flow” It doesn’t seem correct since depth of flow is used to calculate the Hydraulic radius.
- Manning’s equation solves for Velocity. It can be combined with the continuity equation Q=AV to solve for Q (flow rate).
I hope this is helpful to your readers.
Al Collado, PE
I would say:
- Perhaps we should have said "for most of our purposes, where we are calculating for sanitary sewers running half full or storm sewers running full, D/4 is quick way to calculate the hydraulic radius. For other flows, it may only be approximately equal."
- "Mean depth of flow" is not the same as the "depth of flow".
- It is true that Q=AV but one version of the formula incorporates this function and one does not.
David DeBord
May 2011 Black Water Feature
I really hope the US plumbing code community starts to accept and understand the need for innovative thinking such as the systems described in the “blackwater reuse” article Mr. Fisher authored for your magazine this month. Given the fact that the national code community has just gotten around to considering the possibility of accepting the Philadelphia City’s Plumbing code, as an acceptable means of venting, after 100+ years of practical use, my hopes are somewhat dampened. However, this was an excellent article, and brings to mind 2 questions:
If we are talking about packaged local sewer treatment plants, and are using ROI as a intelligent reason for implementation, does the author have any thoughts regarding how much additional cost would there be to include a methane recovery (anerobic digestion) component, to offset utility costs, and further accelerate payback? Methane offgassing is considered a big component of global warming, and is best captured and utilized as close to the source as possible.
In “sewered applications” how likely would it be that problems could develop with so much greywater being recycled and high performance low flush fixtures, that there wouldn’t be enough liquid waste in the system to carry the waste through the pipes? I suppose this would be a good problem to have, but does it need to be considered?
A great article, and I appreciate Mr. Fisher taking the time to document his findings.
Todd Kieninger, PE
The Design Collaborative
April 2011 Water Heater Sizing Article
I enjoyed your article on water heater sizing in the April PS&D.
As we do quite a bit of work in this area ourselves, we were wondering if you consider the effect of hot water at usage temperature circulating through the building pipe work and whether you consider recovery to system set point acceptable in your calculations.
We are learning, to our continuing amazement, how small an amount of hot water typical buildings actually use and for how long. It seems that water heater over sizing is rampant.
We know that a 12” length of 2” pipe holds .375 USGPM. It does not seem unrealistic that there would be 2000’ of pipe in a facility of a given size (BIM can likely tell us to the inch). With a good water temperature controller (like our DRV80 – last commercial I promise) where 120F can be guaranteed minus system radiant loss, then there is 750 Gallons of water in so called “moving storage” to add to the equation.
In addition, you mention at the top of page 16 a one hour peak load period which seems typical. It seems we are always concerned about calculating the recovery back to water heater set point but we wonder whether the building actually cares about that. The real requirement seems to be recovery to system set point which quite often could be 20-40 degrees below water heater set point thus would not take as long.
It all comes down to selecting an accurate water temperature controller (sorry – I did promise). Thanks for writing the article it has been e-passed around our network multiple times.
Best Regards, Paul L. Knight, Armstrong Hot Water
March 2011 Solar Thermal Article
Very good article on solar thermal freeze and overheat. I do have some comments:
1. Drainback systems are not limited to 6 panels to ensure proper draining. We have a 168 panel system going strong at Naval Air Station Jacksonville for pool heating.
2. You don’t need to vent the drainback. You can but it is not necessary. In fact, most of the systems we engineer are not vented on the collector loop.
3. It is not necessary to install a vacuum breaker on the collector loop. If the collectors and exposed piping are slopped ¼”per ft, you will evacuate the panels.
4. With a nonvented drainback system, you can charge it with just tap water. As long as you are not adding more water, you really don’t have to worry about calcium carbonate or other contaminants.
John Alger, Alternate Energy Technologies
March 2011 Backflow Prevention Article
Regarding Ray Parham’s article in March 2011 titled “Backflow Prevention 101”, he states, “…I recommend putting a strainer in front of all RPBP and double-check valve assembly devices.” While I agree with this for all plumbing applications, I was informed by at least one vendor (Wilkins) not to put strainers on fire protection backflow preventers. According to the Wilkins Model 350 series installation instructions, “Do not use a strainer in seldom used emergency waterlines such as fire lines.” When I asked them why, they said something to the effect of: the risk of something clogging the strainer and preventing/reducing flow to the fire sprinkler system in an emergency is greater than the risk of something interfering with a check valve in the backflow preventer and possibly allowing backflow.
Brian Stoltzfus, P.E., CPD, Plumbing & Fire Protection Lead Engineer, Integrated Project Services - IPS
I agree with Brian’s comment. The article should have stated to install a strainer before all RPBP and DCVA in the domestic system. There should not be strainers on the backflow preventers for the fire protection service.
Thanks, Ray Parham
March 2011 Lessons Learned
Your article hit me as a wake-up call in that I started to do the same thing you alluded to in your article, but had said to myself:"Am I crazy?"
I am in the process of retiring from the medical field, in the 70's, selling medical equipment, and since 1994, have been a medical gas inspector/certifier/verifier for the Health care industry.
Recently, I decided to start an "Information Only" newsletter relative to the design, construction relative to code requirements of NFPA and the ASSE 6000 Standard. This may not be in your field, but I have attached my March's edition for reference sake.
You are correct, if not me, who else will pass along knowledge given to "us" by .....? At age 68, I still have a lot to offer, I think, and your article has given me a kick in the rear, letting me know that what I am doing is the right thing to do. For me and my piers.
Thanks again. I will be forever grateful that someone, like you, wrote an article like this.
Rich Schaefer
January/February 2011 Designer's Notebook
Ironically, this week I am designing 5 Sump basins on a project we are doing for a Hospital in Nebraska. While I found the article was a very good basic explanation, I was hoping for a a little bit more in depth. Concerning fiberglass basins, the “Basin Material” section mentioned the need to address Buoyancy, but there was never any mention of when this is required, concrete pad calculations, the importance of specifying the correct fasteners and rebar reinforcement. For calculating the concrete anchor pad, I figure the basin filled with water, then calculate the weight of the water which will be the pad weight. Basin volume CU. FT. x 8.34 = weight. Then Weight/150# = CU. FT. Concrete. Talk to your structural Engineer for sizing reinforcement & fasteners.
Also, when I referenced the ASPE 2006 V3 Design Handbook, Buoyancy and API standards are mentioned, but again there are no buoyancy calculations. I agree this should be coordinated with your structural counterparts, but it should be the plumbing designers responsibility to coordinate requirements.
In the “Sump Basin Sizing” section, a “good rule of thumb” is mentioned. A better solution would be to ask your Civil Engineer what the correct flow would be. They have knowledge through testing of what is specific to your site. They better understand how water is moving through the ground and what the seasonal ground water levels are. If you are in the water table, ask for the cubic feet per day and translate that to GPM for proper pump and basin sizing. You will be shocked the first time you talk with your Civil Engineer on this subject.
Take Care, Dan Martyn
November 2010 Green Column
I read your article with interest. There are however some observations that I would like to share. Over the years we have used many heat sources including multiple brands of water heaters and boilers. In recent years we have worked with the tankless industry to develop tankless gas water heaters that will allow circulation with out a tank and give us more total load capacity. Your article references these products as "point of use or demand" heaters. You should go to
and sign up for the classes they provide for free. These units will today give you 10 thousand to 9 million BTU in operational range.
They are modular allowing redundancy far beyond any boiler or tank system we have ever used and they are available in ASME and stainless steel condensing models. The condensing models are upwards of 98%.
As to installation cost again I can say from experience that a bank of tankless that does not require the crane to set the skid or the combustion analyzer to balance the system at start up are around half the cost to install.
As to "cold water sandwitching" again a thing of the past.
I respect the folks that take their time to supply us with data so we all can do better jobs. The technology has certainly out paced the markets information chain. We all are victims of technology speed. I look forward to reading your articles and hope my input helped you see the improvements in Tankless technology for our industry.
November 2010 Forensic Engineering
I read with interest, the Article by Mark Passamaneck. P.E. on fire sprinkler systems with antifreeze.
The article is nicely written. I wish to bring up the issue of fire fighters entering a building, specifically a residence where the sprinkler system has antifreeze in it. Should a sprinkler head open above or near a fire fighter, said fire fighter will be doused with antifreeze. I'm not sure if this will require haz-mat procedures; but, the turnout gear, including radio and SCBA gear will be a mess.
I'd like to hear from people in the fire service regarding this situation.
As an aside, I do note that Tyco now has listing on a residential dry pipe system.
I greatly enjoy your magazine. Keep up the great work.
Regards,
James S. Nasby, President, Columbia Engineering
October 2010 Designer's Notebook
October 2010 Designer's Notebook
I read your article "What a Plumbing Designer Needs to Know About Designing Irrigation Systems". So when I as a Plumbing Designer, go into a new project, with the knowledge of designing and laying out an irrigation system, and the project has a Landscape Architect on board to do the actual design and layout of the irrigation system, then to what extent, (in your opinion), am I to get involved with the design and layout? I only ask because I have run into situations with other trades, namely the Architect, where if I become involved with an aspect of a project that truly is not my "trade", then somehow I become liable and to blame for it.Typically the extent of my involvement with the Landscape Architect is to provide them with the pressure available, a capped and valved irrigation tap, (of a determined size, with backflow prevention device), and the location to interface with my plumbing system.I have done projects where the irrigation water is metered separately and some where it is not metered separately. I also typically note on my plumbing plans that the irrigation system is to be operated during "non-peak" hours only.Are you implying that myself as the Plumbing Designer, needs to re-check there design calculations and there layouts?
Thanks, Jeff DeMoss
If a landscape architect is involved in the project the only involvement you need to get involved with (in my opinion) is to make sure there is a water line and pressure for them to connect too. If a Civil Engineer is involved they can provide the water connection from the site water main. You can assure that there is enough pressure to operate the irrigation system. If this happens assure the Architect that it is not in your scope. But if he wants you to handle it then he will need to give you the hour/fee to do it. I truly suggest you don’t connect the irrigation system to the building plumbing system. If the pressure is available the irrigation system can operate during the day but typically I see irrigation systems running very early in the morning before working hours. If you are not doing the design you don’t need to check the landscape architects calculations. I want to imply that if an irrigation system is included in the design for you as the plumbing engineer to coordinate with the landscape architect to assure there is adequate water pressure and line size because most landscape architects do a performance spec which is given to an irrigation contractor to do the design for review. And it has been my experience that the landscape architect are not concern with pressure and location of the water line. I hope that these answer any of your concerns or questions.
Joe Messina
July/August 2010 Residential Fire Sprinklers Article
The article on residential fire sprinklers was lacking in that it did not address how homes with private wells, especially those that yield less than 13 gpm, would supply enough water to satisfy the flow requirements of the sprinkler system and the costs associated with meeting minimum flow requirements. Here in Northeast Pennsylvania a great number of homes have water supplied from on-site private wells. Our own well has a yield of 4 gpm, similar to many others in the area. The "Rebutting the Myths" section of the article states that the minimum flow for two or more sprinklers heads is 13 gpm. Will new homes with wells that yield less than 13 gpm be required to drill multiple wells to meet the flow requirements or will large storage tanks be required? When wells can cost upwards of $9000 each this can be an expensive proposition for prospective new home builders.
Regards, Ron Jenkins
September 2010 Domestic Hot Water Article
I recently read the article by Raymond Parham about sizing domestic water. It was a well written article and it explains the basics very well. But it brought up a question that I have been wrestling with lately. Parham mentions that the sizing of the pipe is based on Hunter’s curve. This is the way that I have always sized pipe. This is the way everybody sizes pipe. But is it still applicable today? In this same issue of PS&D there is an advertisement for copies of the Original Hunter Papers on page 45. How old are Hunter’s curve and the other related sizing data? 40 years? 50 years? 60 years?
Where is the update to Hunter’s curve? Nowadays even a standard flush valve toilet is only 1.6 gpf. Lavatories are routinely designed for 0.5 gpm. And yet we’re still using data from years ago. Even Parham acknowledges this in his article, stating that “the actual flow rates based on Hunter’s curve (are) high”. But no engineer or plumbing designer is going to down size a supply pipe because of low flow fixtures. If the design were called in to question the standard of care for sizing supply piping is Hunter’s curve. Not because it’s right. But because everybody else is doing it. And they have been doing it for years and years and years.
So, ASPE, where is the update to Hunter’s curve?
Erik Johnson, PE
Thanks for your comments and interest in my article. To start, I am sure that you are aware that I can’t speak for ASPE, so I will give you my opinion in addressing your questions.
It is my understanding that the frequency data used by Hunter to develop his flow information has been investigated and has been determined to still be valid. This is understandable if you think about the use of water closets and urinals. Further, I think that for the most part people in the U.S. take about the same number of showers or baths for about the same duration today as they did 50 years ago. Finally, we may make more frequent use of lavatories or sinks with the hygiene emphasis today, but it doesn’t appear to be significant enough to invalidate the frequency information for residential or commercial types of facilities. All bets are off for assembly occupancies, but the design community has known about that for years.
So, the real issue is figuring out the impact of low flow fixtures. Unfortunately, it is not as simple as taking a straight ratio of the old flow rates versus the new flow rates. The actual peak flow rate of a 1.6 gallon per flush flush valve is not much different that the peak flow rate for a 3.5 gallon per flush flush valve, it simply lasts for half the duration. The same can be said for metering faucets for lavatories. We can still legally use 2.2 or 2.5 gallon per minute faucets as long as the total discharge volume is .125 gallons per cycle. If 0.5 gpm faucets are used, you will obviously get a much lower flow rate.
However, the real answer to your question is that there simply is not enough money involved in potential downsizing the plumbing system piping to warrant a lot of research. And engineers are some of the most conservative people on earth; they are not going to take a lot of risk in completing designs. In doing research for the article, I asked one of the local plumbing contractor the difference in the installed cost of 3/8” vs 1/2" Type L copper tube. His response was $0.17 per foot in material costs only, labor was the same. So if there is 1000 linear feet of 1/2" copper that could be replaced with 3/8”, the owner saves $170. You may have a 40 foot long 3” water riser that could be replaced with 2-1/2” piping and save $200 to $300. All told, you might save $5,000 on a $30 million building.
So, outside of using good judgment on when it is appropriate to use smaller pipe size (primarily for domestic hot water as I outlined in the article) for bathroom group piping, I use Hunter’s Curve flow information and recognize that the system will be oversized. The good part of this is that the owner will be able to add lots of fixtures in the future and will not have to worry about replacing a lot of pipe.
Hope this helps. Raymond F. Parham, PE
June 2010 Rainwater Harvesting Article
Refer to page 29, refer to Total system size and tank capacity calculation example. Please confirm if the multiplier of 0.5 is wrong. The correct multiplier should be 0.623
Regards, Happy Wong, CPD
Some designers use 0.50 gallons/square foot/inch for the accumulation of rainwater on a roof surface instead of 0.623 to account for leakage, evaporation and deflection of the initial "flush" quantity. I believe that this results in a more conservative estimate.
Peter S. Cartwright, PE
Venting 101 - Jan/Feb 2010 Issue
In the January/February 2010 PS&D issue, you wrote an article about "Venting 101 - Learn What You Need to Know to Start Designing a Venting System" and on page 25, you stated that "Nothing, however, can destroy the effectiveness of a vent system faster than combining it with a sewage ejector vent or a grease interceptor vent. Always remember to keep them independent."
What is the reason for having a seperate vent line for a sewage ejector and grease interceptor that vents up through roof?
Best regards, Ralph Bautista
Code requirements suggest but do not always require that a sewage ejector be vented separately:
UPC 710.10 Sumps and receiving tanks shall be provided with substantial covers having a bolt-and-gasket type manhole or equivalent opening to permit access for inspection, repairs, and cleaning. The top shall be provided with a vent pipe that shall extend separately through the roof or, when permitted, may be combined with other vent pipes. Such vent shall be large enough to maintain atmospheric pressure within the sump under all normal operating conditions and, in no case, shall be less in size than that required by Table 7-5 for the number and type of fixtures discharging into the sump, nor less than one and one-half (1-1/2) inches (40 mm) in diameter. When the foregoing requirements are met, and the vent, after leaving the sump, is combined with vents from fixtures discharging into the sump, the size of the combined vent need not exceed that required for the total number of fixtures discharging into the sump. No vent from an air-operating sewage ejector shall combine with other vents.
Notice that the size of the vent is "large enough to maintain atmospheric pressure", but most engineers just use the size in Table 7-5. This is often too small. You need to understand that when the ejector basin is filling up, the vent is under positive pressure created by the fixture units flowing in. When the pump kicks on, the vent and the waste inlet pipe (and all of its connected vents) are quickly under negative pressure created by the discharge. This negative pressure is far greater than any other because what slowly collected over time is discharged in 3 to 5 minutes. That negative pressure can siphon an upstream trap allowing sewer gasses to enter the building once the pump stops.
Grease interceptors have two problems. The first, similar to sewage ejectors, is that they collect and store waste. This makes them much more odorous than a properly sloped waste pipe. If that pipe is routed separately to the roof, it can be better isolated from outside air intakes and the like. If it is connected to a common vent system, it is almost impossible to predict where the smell will travel and the minimum 10 foot separation of vents through the roof is often not enough. Notice the word minimum that is so often ignored by designers and installers.
The second problem with grease interceptors is lack of maintenance. The interceptor has a baffle separating the waste below the water line into two chambers while allowing the air above the water line to circulate. If (when) grease builds up within the unit and blocks the space above the baffle, the unit becomes air-bound. This allows waste entering the first chamber to compresses the air which then "burps" through the vent or any available pipe.
I hope this helps.
Regards, Peter Kraut, P.E.
Thanks so much for taking the time to respond. However, I am still trying to understanding how a fixture trap will self-siphon when the pump kicks on. Is the vent on the sewage ejector not enough to prevent fixture traps self-siphonage along with all the vents connected to each fixture traps. In what cases would the self-siphonage occur? I tried thinking of ways to siphon out the trap seals but I still cannot imagine this happening due to the vents.
As for the grease interceptor vent, what if you are designing a hospital that requires you a minimum of 25ft seperation? For the most part, a lot of mechanical equipment are on the roof that makes it hard to locate the vent through roof of a grease interceptor. Would you recommend combining it in the vent system at this point?
Air flow in vent pipes is quite complex and almost never studied or calculated to this extent. All I can tell you is that I have investigated dozens of vent odor problems in the last 10 years and to the best of my recollection, every one of them had a sewage ejector and/or an interceptor tied to a common vent. Furthermore, most of them had a branch vent sized per code, but given the force of air leaving the pipes, it was clearly not "atmospheric pressure" as required by code. I do not recommend combining them and I encourage you to route them as far away from air intakes as possible, not just the code minimum distance.
Designer’s Notebook for May 2010 Issue
Mr. Messina hit one out of the park with his evaluation of Value Engineering. I too agree that VE is a wasted effort when the project calls for either quality equipment or design. The best line regarding VE came from Chicago Engineer Dick Kviz…”I Value Engineered the project when I designed it…afterwards call it what it is …Cheap!”
Value Engineering: What Is It?
Mr. Messina, I liked your last paragraph best. Competent engineers don't need "value engineering," because they practice it continually. The problem is that a value engineering team cannot make a poor design into a good one. When I graduated, it was assumed, and rightly so, that a green graduate needed mentoring and training to become a functioning engineer. Unfortunately, primarily because of financial pressures, today these green engineers are assigned to projects above their "pay grade" and instructed to meet a minimum level of billable hours with little, if any mentoring. I'm sure you remember Compressed Air Magazine as fondly as I do. It served no direct beneficial function, so it became extinct. It stimulated creative thought, what a novel concept.
Carr Baldwin, PE
Laboratory Plumbing 101, PS&D April 2010
Jim Williams, I read and enjoyed your article on Lab Design very much. I am a retired Plumbing Design Engineer (now a NJ State licensed Plumbing Subcode Official/Inspector in the township where I live) and I agree with all your suggestions and reasoning for good design practices. Let add a few extra “red flags” to be aware of, during your design: Listen to and understand the people who will be actually using these lab facilities, then explain your design methods and reasoning to them, as though they were 6 years old. Emphasize the importance of how these systems and equipment must properly be used, your pipe material selection and pipe sizing reasoning. Find out the true concentration levels of chemicals that will be used, then add a safety factor of 20%. Certain pipe materials are only good for low amounts of certain chemicals. Check the chemical resistance charts of all the pipe materials selected, then give a copy of these charts to the client for reference and to CYA. Check the proper pipe joint methods and materials used, e.g., type of gaskets and their approval rating for such chemical applications. Check proper supporting of these pipe systems…very critical. Visit the site at selected intervals during construction to check on the proper methods of installation…a progress report/check. Any contractor change of piping material, devices, valves, equipment, etc. MUST first be approved by the Plumbing design engineer…PERIOD. These are just a few items that I have run into during my 34 years of Plumbing design/engineering….now I am witnessing these again as an inspector.
Gerald Recigno, CPD
Conducting a Plumbing Field Survey
I would like to comment on James Stenqvist’s April article “Conducting a Plumbing Field Survey.” The checklist was quite complete except for one item, the piping material for any of the plumbing systems. It is important to identify the materials so as to determine the condition and if that material will be compatible with any new system renovation. Many years ago a Survey Report was prepared by a consultant for one of our older campus buildings, anticipating a major seismic up-grade project. The report stated that the domestic hot and cold water piping systems were threaded galvanized steel pipe. The report assumed that the condition of the pipe was very poor and should be replaced. The building was built in 1934 and never re-piped. A red flag went up. I did not think a steel pipe system would have lasted that long. All of the exposed piping in the building had been painted many times, so the original pipe finish was not apparent. I did a field test with penknife and file, removed some paint, and found Brass pipe with Brass screwed fittings: a better material by far. We had our campus plumbers remove sections of pipe for inspection. The interior of the pipe was as clean as the day it was installed. When the renovation project was designed, much of the original water pipe was left intact. The material for those sections that were required to be replaced, and any new pipe was K copper.
Steve Sebolsky