Re: check valve

From: <rajendra>
Date: Thu Oct 30 2003 - 04:54:00 EST

Dear Paul,

I have seen some new Ball type Non return valves shaped like a standard Y strainer with the Y arm pointing upward. A Ball is placed in the passage of the fluid. Due to the fluid presssure, the Ball is lifted up in the arm of the 'Y'. I will try and load a picture of this if I can manage to. Judging from the configuration, it does not seem to better the existing NRVs. Lakshmi has not mentioned which kind of Ball type NRV he has referred to. The Ball valve type or the Ball type I have mentioned here.
Regards,
Rajendra Bajikar.

Paul Bowers <pbowers@pipingdesign.com> wrote: Ball checks are similar to globe valves in layout in the sense that the flow tends to be up and over (or around) rather than a "straight-through" pattern that wafer checks have. This would seem to result in more turbulence and higher pressure drop.

My experience in refineries that were built 60+ years ago indicates that at that time there were limited alternatives as to check valve choices and wafers don't exist in the original specs. Same goes for high-performance butterfly valves.

If you are unsure, consult an expert for the intended fluid and pressure application.

If you are diverting from original plant specs and rely on supplier recommendations, I STRONGLY suggest that you check out the supplier.

In the past, stuff has blown up because products looked good (for the price) but actually were non-code. We don't want to kill anybody here.

Paul

• Original Message ----- From: "Lakshmi V. Narayana" To:

Sent: Wednesday, October 29, 2003 11:39 PM Subject: FW: [PipingDesign] check valve

> It is availble with the vendor that he can supply rightaway.enough space
is
> avialable. wafer is replaced with ball type. pressure loss is very less.
>
> regards
> lakshmi narayana
>
> -----Original Message-----
> From: rajendra bajikar [mailto:rajendrabajikar@yahoo.com]
> Sent: Wednesday, October 29, 2003 8:40 AM
> To: PipingDesign@yahoogroups.com
> Subject: Re: [PipingDesign] check valve
>
>
> The Non Return Valve, whatever type you use, is to prevent back flow. You
> may want to check out the pressure losses between the two, if it is
critical
> in any way. You have not mentioned the reason for this change.
> Regards,
>
> "Lakshmi V. Narayana" wrote:
>
> Dear friends,
>
> Instead of wafer type check valve(PTFE lined),PTFE ball type check valve
is
> being used for oily water service (3"NB) pressure 4KG/cm2 temp 44C . is
> there any negative impact in doing so. can anybody throw some light on
this
> .
>
> Regards
> LAKSHMINARAYAN
> MECHANICAL ENGINEER
> SAFCO

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Rajendra Bajikar.

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[Non-text portions of this message have been removed] Received on Thu Oct 30 04:54:00 2003