Swing Check Valves

Al Corelli_2

Before the BFP or after it?

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BAB

Swing Check Valves

The condensate return air is vented from the condensate pump chamber thru a ¾” swing check valve. The most that valve sees is ½ - 2 psi air at room temperature. Due to equipment vibrations and/or other unknown factors I am not convinced the swing check valve is always closed when it should be. I read somewhere about mounting the swing check at a 45 degree angle to make the swing flapper almost horizontal. This field fix is supposed to make sure the swing check flapper is closed when it should be.

Also I investigated spring loaded check valves but can not get information on lowest (minimum) opening pressure. I want it to open on anything over 0 - ½ psi. Want a very definite close at zero psi, room atmospheric pressure. Any suggestions or advice ?? Bromley

Gene_3

check this

http://www.spiraxsarco.com/resources/calculators/pipes.asp

http://www.spiraxsarco.com/resources/steam-engineering-tutorials/condensate-recovery/pumping-condensate-from-vented-receivers.asp


if you can't find it call them, Spirax is very helpful

EBEBRATT-Ed

Look around at the supply houses and you can find a swing check with an angled seat set at about 45 deg. I am sure they are available. Nibco t-413 or t-433 would do it.

ED

mike@BORO

DOUBLE PROTECTION?

Met an inspector today [nyc . boiler]first test to get oil burning permit etc. loved the job , however he pointed out that a swing check is now mandatory, beside the backflow which was already there on the makeup water line going to the cond. return. FOR WHAT? Can someone explain? met another inspector in the afternoon for another test , and he also gave me the same news. cant get a straight answer'

Canuck_3

I know that there can be some nuisance service calls on the BFP if a check valve isn't installed downstream of the unit. The BFP relieves, which it's supposed to do, but sometimes doesn't reset or the discharge isn't piped to drain properly and makes a mess. If the BFP discharges a lot, then there's a lot more make-up water going back in, which isn't the best either.

Canuck_3

After (downstream). This way the BFP may not actually "see" a backflow condition because the check valve has already caught it. If the check valve fails or misses the reverse flow condition, then the BFP is still in place to catch it.

Robert O'Connor_12

?

specified in this Advisory BOILER REGULATION ADVISORY

Subject: Use of a backflow Preventer in Boiler Applications

In accordance with the regulatory authority granted by the Boiler, Pressure Vessel and Refrigeration Laws, this advisory is being issued to ensure safety of the general citizenry in the installation, repair and operation of boiler plants which includes the appurtenances, devices, controls or any items that directly or indirectly impacts upon the regulated equipment that could potentially pose a hazard to the public. Specifically this advisory addresses the use of a Backflow Preventer (BFP) in all boiler related applications.

This advisory responds to numerous inquires that have been submitted concerning the position of the Bureau of Boiler and Pressure Vessel Compliance (BB&PVC) on the acceptance of ASME interpretation IV-95-02, future ASME Code addenda regarding BFP, and other written requests for an official determination on the acceptable use of a BFP in boiler applications that fall under the BB&PVC's jurisdiction.

The BB&PVC does not concur with ASME Code interpretation, IV-95-02 and officially declares any future ASME Code addenda allowing such installations as invalid for the reasons that follow. The BFP and the check valve designed for two disparate purposes and made to accomplish two distinct functions. The check valve required by Section IV, HG-705(a)(b), is intended for the sole purpose of preventing the water in the boiler from being forced out under pressure in the event of a piping break or loss of supply pressure. The backflow preventer is intended for the sole purpose of preventing normally contaminated (undrinkable) water found in the boiler from back-flowing into the potable water system as is required by the plumbing codes.

The BB&PVC staff has thoroughly reviewed product information from the manufacturer of a commonly used BFP. According to this manufacturer's documentation and information obtained from their corporate technical staff, their BFP has rubber-to-metal valve internals that would not be able to tolerate an incidental temperature excursion of 250 degrees F without failing. These types of excursions might be experienced by low-pressure boilers during abnormal or malfunctioning conditions and as a result would melt the rubber internal components, which according to the design of the BFP would open the port to the atmospheric vent so as to prevent the undrinkable boiler water from contaminating the potable water supply. When this vent opens it creates an unacceptable event for boiler operation, because the melting internal component in the BFP puts the boiler at risk for dry-firing condition which could result in a catastrophic failure or a boiler explosion.

For obvious reasons, the melting of protective components is not acceptable for safety and contradicts the logical reasoning for the installation of a standard boiler check valve. Acceptable engineering practices requires that the valves, devices, controls and other similar appurtenances or appliances attached to the boiler or that are an integral part of the boiler, be engineered to prevent a catastrophic failure. Clearly, the BFP installed by itself in the potable water supply line to a boiler defeats the practical safety applications meant for the various devices and components used in boiler systems.

The BB&PVC as the jurisdictional authority has determined that the installation of the BFP the way it is presently (#1) engineered, must not be used by itself in the potable water supply line to the boiler as a replacement for the simple design and standard issue metal seated check valve. In addition, when the installation of the BFP is required by the plumbing codes in the potable water supply or makeup line to the boiler, it shall include the standard check valve as the required by the (#2) boiler safety codes and standards. Thus, the required metal seated and standard check valve must be installed downstream of the BFP, and include a shut-off valve next to the boiler and be located downstream of the standard check valve for system isolation and maintenance purposes.

Therefore, in accordance with N.J.A.C. 12:90-4.2(e), where it states that "only standards relating to public safety are adopted by any incorporation by reference as prescribed ect". The BB&PVC has conclusively determined that the ASME Code Interpretation IV-95-02 and any subsequent Code addenda or revisions regarding this Advisory topic is not in the best interest of public safety for boiler operation thus is ruled invalid. Therefore, in accordance with this advisory any standard check valve and shut-off valve found to be installed in any other manner described herein shall be deemed to be in violation of the BB&PVC regulations and the owner will be subject to the monetary per diem penalty assessment until abatement of the violation occurs.

All questions regarding this advisory should be directed to the BB&PVC by calling (609) 292 2921; by email to the Bureau Chief: MiltonWashington@dol.state.nj.us by Fax at (609) 984 1577, or by written request to the address below.


Department of Labor and Workforce Development Labor Standards and Safety Enforcement Division of Public Safety and Occupational Safety & Health Bureau of Boiler and Pressure Vessel Compliance P.O. Box 392 Trenton, NJ 08625-0392


Signed: Milton Washington Chief, BB&PVC


(#1) The BB&PVC recognizes that technological advances occur that could address the safety concerns of this Advisory and that improvement in the BFP is possible. However, until advances are made in the design of the BFP to address the concerns expressed, this Advisory shall be enforced and in effect until deemed otherwise necessary.

(#2) See 2004 ASME Code or any earlier code edition of Section IV, "Rules for Construction of Heating Boilers" at paragraph HG-705 for the installation detailed in this Advisory. Until proven otherwise, this Advisory renders paragraph HG-705 of the 2006 ASME Code Addenda and future revisions invalid when the design of the BFP is of the type as specified in this Advisory.

Personally I think the BB&PVC is wrong, and fundamentally cannot do this legally. There has been NO official Code adoption, Nothing has been included in the Registar nor have they responded with any data suporting their position other than alot of mumbo-jumbo as I've written above.

Robert O'Connor/NJ

Robert O'Connor_12

ASME

I finally received a fax from the third party "commissioned" inspection agency. The fax includes a section out of the A.S.M.E Boiler Pressure Vessel Code book. The section reads as follows:

Section (roman numeral) 4 Article 7, paragraph HG-705 a & b

HG-705 FEEDWATER AND MAKEUP WATER CONNECTIONS

(a) Steam boilers. Feedwater or water treatment shall be introduced into a boiler through the return piping system. Alternatively, feedwater or water treatment may be introduced through an independent connection. The water flow from the indepentent connection shall not discharge directly against parts of the boiler exposed to direct radiant heat from the fire. Feedwater or water treatment shall not be introduced through openings or connections provided for inspection or cleaning, safety valve, water colum, water gage glass, or pressure gage. The feedwater pipe shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler or between the check valve and the return pipe system.

(b) Hot Water Boilers. Makeup water may be indtroduced into a boiler through the piping system or through an independent connection. The water flow from the independent connection shall not discharge directly against parts of the boiler exposed to direct radiant heat from the fire. Makeup water shall not be introduced through openings or connections provided exclusively for inspection or cleaning, safety relief valve , pressure gage, or temperature gage. The makeup water pipe shall be provided with a check valve near the boiler and a stop valve or cock between the check valve and the boiler or between the check valve and the piping system.

Now, on to the "Official" INTERPRETATIONS Volume 36 of the ASME Boiler and Pressure Vessel Code SECTION (roman numeral) 4

INTERPRETATION: (RN) 4-95-02

Subject: Section (RN) 4, HG-705(b) and HG-715(c)

File: BC94-353

Question: May a backflow preventer containing a check valve be used to satisfy the requirements for a check valve per paragraph HG-705(b)?

Reply: Yes

Any questions?

POC for the New Jersey State Boiler and Pressure Vessel Compliance is Milt Washington (609) 292-2345


Robert O'Connor/NJ