INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

If you want to learn more, please visit our website Disai.

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!

• Talk With Other Members
• Be Notified Of Responses
  To Your Posts
• Keyword Search
• One-Click Access To Your
  Favorite Forums
• Automated Signatures
  On Your Posts
• Best Of All, It's Free!

Join Us!

*Eng-Tips's functionality depends on members receiving . By joining you are opting in to receive .

Posting Guidelines

Students Click Here

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Eng-Tips Posting Policies

Contact US

Check valve installation procedure

thread408- Forum Search FAQs Links MVPs

• Forum

• Search

• FAQs

• Links

• MVPs

Check valve installation procedure

Check valve installation procedure

gustorf

(Mechanical)

(OP)

19 Mar 08 10:04

Dear All,
We all know that check valves should be installed at least 3 x DN behind the discharge of pumps, not on 90° ellbows, at least 2 x DN before any downstream valve, etc.
This is common engineers knowledge, but where in the literature is this written?

RE: Check valve installation procedure

pennpiper

(Mechanical)

19 Mar 08 11:55

Where did you see or hear that?

After more than 45 years in the piping business I have never heard of such a rule.  
I say it is bunk.

I put in a lot of top discharge pumps where the piping after the discharge nozzle was a flange, a reducer a flange and then the check valve.

Please tell us all where you saw this.

RE: Check valve installation procedure

stanier

(Mechanical)

19 Mar 08 16:56

The reason is that there can be turbulence from the pump that increases the wear of a check valve and lead to its failure.

There was an ASTM standard that covered this topic.

Many check valve manufacturers have in their literature a requirement for 5-6D between pump discharge and check valve. In fact Velan recommend 10D.The reason is that there can be turbulence from the pump that increases the wear of a check valve and lead to its failure.There was an ASTM standard that covered this topic.

RE: Check valve installation procedure

pennpiper

(Mechanical)

19 Mar 08 19:25

gustorf (Mechanical)

At this point you have gotten two different opinions.  These two opinions are at the opposite end of the scale.  
So what do you do?
Well I suggest that you buy "Process Plant Layout and Piping Design" by Ed Bausbacher and Roger Hunt.
You can find it on Amazon(dot)com
Chapter 8 (page 181) covers pumps and pump piping very well.  Read it and then go out to a Refinery or Chemical plant and look at all the pump installations.  If you can take pictures do so.  If you cannot take pictures make a sketch of all or as many as you can and get the service and design conditions (pressure & temperature).  Then take a few dimensions.
Decide for your self what is right.

RE: Check valve installation procedure

pennpiper

(Mechanical)

19 Mar 08 19:53

stanier (Mechanical)
You are indeed a prolific contributer to the "ENG-TIPS Forum" and with out going through all 124 of the threads you have started or the 1,139 replies to other people's question or even the 93 replies you made to your own threads I must accept that you are knowledgeable about what you speak.

However, on this subject I think you may be mixing up the Hydraulic Institute recommendations for pump suction piping for an end suction pump.

If Velan has such criteria I cannot find it and I cannot fine it in any other valve vendor's technical literature.
 
If "ASTM" addresses this subject please furnish the number of the Standard.  Also if ASTM is "American Society for Testing and Materials" why are they addressing check valve installation position relative to a pump discharge?

I also checked with a colleague (35 year piper) and we are in agreement that you are confused and giving wrong information to gustorf .

RE: Check valve installation procedure

insult2injury

(Mechanical)

19 Mar 08 20:08

Pump discharge pressure and flow fluctuations, turbulence, etc. can cause increased wear on the check valve. Most valve manufacturers will recommend long lengths between piping components. While this is good practice, it is not necessarily required as the manufacturers will agree. In most applications, the process conditions are not severe enough to cause a noticeable difference in valve life and maintenance. By following the piping guidelines mentioned, no valve should fail prematurely due to improper layout. My advice is...if you can accomodate it, do so...otherwise ask the manufacturer to take a look at your specific application (not all vendors will agree to do this however).

I2I

RE: Check valve installation procedure

stanier

(Mechanical)

19 Mar 08 23:46

Rather than dig up statistics on my postings perhaps a search of Eng-tips on this subject would be better time spent. Here is the ASTM reference  

I also suggest reading of test work by Delft laboratories and texts by Professor ARD Thorley.

I have seen this requirement quoted in company standards and in manufacturers' literiture else I would not have mentioned it. As recently as yesterday I was reading the Velan literature provided to me by a valve company other than Velan.

This is not necessarily a question addressed by a "piper" but  more for a mechanical engineer in the business for 42 years.

Pennpiper,Rather than dig up statistics on my postings perhaps a search of Eng-tips on this subject would be better time spent. Here is the ASTM reference http://www.eng-tips.com/viewthread.cfm?qid=&page=61 I also suggest reading of test work by Delft laboratories and texts by Professor ARD Thorley.I have seen this requirement quoted in company standards and in manufacturers' literiture else I would not have mentioned it. As recently as yesterday I was reading the Velan literature provided to me by a valve company other than Velan.This is not necessarily a question addressed by a "piper" but more for a mechanical engineer in the business for 42 years.

RE: Check valve installation procedure

stanier

(Mechanical)

19 Mar 08 23:55

Also Velan article can be found at
http://www.valvediagnostics.com/installation/check.htm

Isnt Google wonderfully quick!

ASTM should read ASME.Also Velan article can be found atIsnt Google wonderfully quick!

RE: Check valve installation procedure

stanier

(Mechanical)

20 Mar 08 00:39

http://www.tycoflowcontrol-pc.com/ld/F87LIM_5_04.pdf

Here is another reference. Tyco want 10-20D upstream and 5D downstream of this particular rubber flap type check valve.

RE: Check valve installation procedure

gustorf

(Mechanical)

(OP)

20 Mar 08 04:36

Dear pennpiper and insulttoinjury,
Thanks for the input. Beeing in the check valve business just for 17 years, there is still a lot to learn.
I will check out the process plant layout book but couldn't find any info in Prof. Thorley's book.

Our company produces nozzle check valves which in fact CAN be installed in all above mentioned critical installations. I am just looking for an independant written practice to convince engineers about proper installation.

Conventional check valves suffer from turbulences and flow rates too low to keep them 100% open. Nozzle check valves need just about 1 to 1,5 m/s water velocity for stable fully open position and streamline the turbulances by their design.

Dear Stanier, thanks as always.

RE: Check valve installation procedure

TBP

(Mechanical)

27 Mar 08 21:41

If conventional check valves are correctly sized (as in NOT line sized, but smaller) they work just fine. What happens, for example, is that people just put 4" check valves in 4" lines. That check valve likely won't see enough flow to drive it full-open and hold it there. It'll flap like a flag in the wind, and wear out long before it should.

 If the line is sized correctly (as in not oversized), the proper conventional check valve will very likely be one pipe size smaller - a 3" in this case.

Crane's Tech Paper No. 410 has a section on this.

RE: Check valve installation procedure

cheaterbar

(Electrical)

4 Apr 08 07:56

This is from Velan service Manual for Check valves.It mentions 10 pipe diameters.

All piston and ball check valves should be installed
in a horizontal pipe run with the cover up, and the
angle of incline of the line should be no more than
45° from horizontal. Also, the roll angle of the valve
cover should be no more than 45° from side to side
(Figure 2.5D). For vertical flow condition, please
consult the Velan Customer Service Department.
Swing check valves should be installed in an
horizontal, inclined or vertical position. The roll
angle of the valve cover should be no more than
45° from side to side (Figure 2.5C).
NOTE: All check valves should be installed at
least ten pipe diameters away from upstream
pumps, elbows, fittings or equipment. If closer
installation is required, please consult the
Velan Customer Service Department.
WARNING: Soft-seated piston and swing
check valves should not be welded into the
pipeline with the soft-seated disc in the valve.
The disc must be removed and reinstalled after
the valve is welded into the pipeline.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login

Want more information on Nozzle Check Valves? Feel free to contact us.

News

Pressure-activated check valves prevent contamination and flooding from water sources used in fire protection systems

A check valve is a device that permits the flow of semisolids, liquids, or gases in only one direction. Check valves, featured in systems ranging from residential plumbing to pharmaceutical production, often rely simply on changes in pressure to manage flows.

In this article, we&#;ll focus on check valves for fire protection, discussing how they work, the types of check valves, and their benefits in fire sprinkler systems. Additionally, we&#;ll help you understand what components you should look for when selecting a check valve and discuss how to maintain them.

Already know what you need? Feel free to go straight to our check valve product page and selection of grooved riser check valve trim kits.

How does a check valve for fire protection work?

Each fire sprinkler system needs a dependable source of water for immediate use in a fire emergency. Most systems use some combination of gravity tanks, municipal water supplies, and sometimes fire department connections to provide water to sprinkler heads. But while multiple potential water sources provide an extra layer of reliability to fire protection systems, they can also be problematic: drinkable water might be contaminated by water from a fire hydrant, or dirty water from fire sprinkler pipes might flow through nearby streets and into nearby drains. In many other applications, it&#;s simply important that water only goes one way for performance reasons. These include protecting equipment such as pumps and filters from backflow damage, stopping drainage in a fire sprinkler system with elevation changes, providing pressure relief in liquid or pneumatic applications, and more.

Check valves for fire protection prevent the unwanted reverse flow of water, known as backflow, from occurring. Many check valves feature a hinged clapper with a spring, which keeps the valve closed until the water flowing from some water source opens it. These clappers only open in one direction: when these flows reverse (or very nearly stop), the spring presses the clapper against a rubber seat, forming a water-tight seal.

Think of the water on either side of the clapper as the supply side (between the water source and the check valve) and the system side (between the check valve and the rest of the system). When a fire sprinkler head discharges, water is released, decreasing the pressure on the system side. Shortly after, the higher pressures from water stored or pumped from the supply side push open the clapper, and water flows through the system.

How does a check valve for fire protection prevent contamination of potable water?

When multiple water supplies serve the same fire sprinkler system, each must have a check valve.

From the Edition of NFPA 13

16.9.4.1 Where there is more than one source of water supply, a check valve shall be installed in each connection.

Check valves decide which source actually provides the system with a supply of water at a given moment. When multiple water sources are used simultaneously, only the check valve connected to the highest-pressure water source remains open. Imagine you have a system with three water sources at the following pressure ratings, expressed in pounds per square inch (PSI):

Active Water Sources Check Valve Status   100 PSI Fire Department Connection (FDC)
75 PSI Gravity Tank
50 PSI City Water
FDC, Gravity Tank, & City Open Closed Closed Gravity Tank & City Water Closed Open Closed City Water Only Closed Closed Open

(Note: these pressure levels are provided only as illustrations and are not meant to be taken as typical for these water sources.)

When water is supplied from all three sources, only the check valve leading to the fire department connection remains open. Why?

Of these three sources, the FDC delivers the highest water pressure. This supply pressurizes the water on the system side. This increased system-side pressure is greater than the 75 or 50 PSI on the supply side of the check valves connected to the other water sources and, as a result, their clappers close.

To continue with this example, if only the city water and the gravity tank supply water, the check valve to the 75-PSI gravity tank will open, while the city water&#;s check valve stays closed. Only when all other sources are exhausted or closed does the municipal water supply open the check valve and flow into the system.

What are the types of check valves for fire protection and their benefits?

There are four main types of check valves for fire protection:

• Alarm check valve
• Swing check valve
• Grooved check valve
• Grooved shotgun riser check valve
• Backflow preventers comprising multiple check valves

An alarm check valve consists of a spring, a valve clapper, and an alarm port. The alarm port can be used to direct water to a water motor alarm or an alarm pressure switch used to alert nearby personnel to the system&#;s activation or send a signal to a fire alarm control panel.

A swing check valve can act as an alarm check valve for a wet-pipe fire sprinkler system, but only when that valve can sound an alarm.

From the edition of NFPA 13

16.11.3 Waterflow Detection Devices.

16.11.3.1 Wet Pipe Systems.

The alarm apparatus for a wet pipe system shall consist of a listed alarm check valve or other listed waterflow detection alarm device with the necessary attachments required to give an alarm.

Typically, these alarms are sounded by flow switches, which send a signal to local alarms and/or the fire alarm control panel when water flows through system piping.

Grooved check valves are a type of swing check valve for use in systems that have grooved-connecting pipe ends. Many grooved check valves can be used in a vertical or horizontal orientation, allowing them to be used in various configurations with a fire department connection, bypass connection, gravity pressure tank, or pump discharge connection.

A grooved shotgun riser check valve is similar to a grooved check valve but includes pressure gauges to monitor the supply and system pressure. The shotgun configuration, which uses an electric water flow switch and an alarm bell, is only permitted in situations where a water motor alarm is not required. Shotgun riser check valves offer a more compact and economical alternative to an alarm check valve.

Finally, there are backflow preventers that are explicitly designed to prevent the contamination of water supplies. They use check valves and extra fail-safes to make absolutely sure water flows one way and doesn&#;t contaminate potable water supplies. You can read more about them in our other blog: &#;Backflow Preventer vs. Check Valve: What&#;s the Difference?&#;

Do check valves require periodic maintenance?

Yes, check valves require periodic inspections and maintenance. For this reason, NFPA 13 warns against burying check valves or positioning them in areas where they will be inaccessible.

From the Edition of NFPA 25

13.4.2 Check Valves

13.4.2.1 Inspection. Valves shall be inspected internally every 5 years to verify that all of the valve&#;s components operate correctly.

13.4.2.2 Maintenance. Internal components shall be cleaned, repaired, or replaced as necessary in accordance with the manufacturer&#;s instructions.

Alarm check valves and system riser check valves require more frequent inspections. Regular inspections help to verify that the clapper functions properly, that the valve seat is in good condition, and that there aren&#;t any visible signs of corrosion or blockages.

From the edition of NFPA 25

13.4.1.1* Alarm valves and system riser check valves shall be externally inspected quarterly and shall verify the following:

(1) The gauges indicate normal supply water pressure is being maintained.
(2) The valves and trim are free of physical damage.
(3) All valves are in the appropriate open or closed position.
(4) The retarding chamber or alarm drains are not leaking.
(5) Where applicable, the valve in the connection to the pressure-type contacts or water motor&#;operated alarm devices are either sealed, locked, or electrically supervised in the open position.

NFPA 25 also requires an inspection of alarm valves&#; internal components every five years.

13.4.1.2* Alarm valves and their associated strainers, filters, and restriction orifices shall be inspected internally every 5 years unless tests indicate a greater frequency is necessary.

Maintenance should be performed by following the guidelines set by the manufacturer. Following an inspection, the manufacturer&#;s guidelines should also be used while returning the system to service.

What&#;s the best brand of check valve? What should I look for?

Every check valve installed on a fire protection system should be FM-approved and/or UL-listed. Listings certify that a check valve is designed to withstand the conditions it&#;ll be exposed to while in use. They&#;re also specifically required by NFPA for check valves on fire sprinkler FDCs and the alarm check valves used with wet-pipe fire sprinkler systems.

From the edition of NFPA 13

16.11.3 Waterflow Detection Devices.

16.11.3.1 Wet Pipe Systems.

The alarm apparatus for a wet pipe system shall consist of a listed alarm check valve or other listed waterflow detection alarm device with the necessary attachments required to give an alarm.

16.12.6 Valves.

16.12.6.1 A listed check valve shall be installed in each fire department connection and shall be located in an accessible location.

In addition, when you&#;re purchasing a check valve for fire protection, you should also consider:

• The size and pressure ratings of your fire protection system
• How easy and fast the check valve is to install
• The quality and construction of the valve&#;s components

QRFS carries UL-listed and FM-approved grooved check valves for pipes ranging from 2 to 6 inches. All of our check valves feature a non-slamming, spring-loaded clapper that forms a water-tight seal against an EPDM synthetic rubber seat. With a durable ductile iron exterior and corrosion-resistant stainless steel clapper, these valves are built to last.

Any of these valves can be installed in a vertical or horizontal orientation. What&#;s more, each can be used as an alarm check valve with a shotgun riser check valve trim kit, available for every check valve we carry.

When you make a purchase from QRFS, you receive quality products at our competitive pricing. We begin processing your order the moment we receive it so we can provide you with the fastest standard delivery possible, generally reaching you in 2-3 business days.

View our selection of grooved, inline, and swing check valves, plus our inventory of grooved riser check valve trim kits.

Questions about this article or our grooved check valves? Call us at +1 (888) 361- or  .

This blog was originally posted by Jason Hugo and Anna Hartenbach at blog.qrfs.com on October 26, , and updated on January 1, . If this article helped you select the right check valve, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

For more check valve leakinginformation, please contact us. We will provide professional answers.