Submersible vs VS4 type pump 1

[vjr0512]

I posted earlier in Environmental Engg. I think Pump Engg is the correct forum to place this query.

Contractor requests to go for VS4 type vertical submersible pump instead of earlier proposal of Submersible pump as the zone classification of these lift stations are now considered to be one 2. They say that submersible pump motors cannot be made suitable for Hazardous zone.

Is it agreeable to accept the contractor proposal so that the motor is complied with the required classification.

As for as i have come across in various installations, all the lift stations pumps are submersible pumps only.

Thanks in advance for your reply

 

[Artisi]

Are you asking flameproof/explosive proof submersible pumps? These are available but as no operating conditions / site data is given, cannot make any suggestions.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[vjr0512]

Thanks artisi for your reply. Yes. The zone classification is Zone 2. The service is oil contaminated effluent water.

 

[Artisi]

Look at Flygt pumps.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

Maybe it's me but if the submersible pumps are actually submerged in liquid, how can they be in a zone 2 area?

Of course if the motors become exposed then they need to be suitably certified, but if they can't operate unless submerged then what's the problem?

It sounds like someone might not have appreciated when and where you need said motors??

More data needed about the location of the pumps relative to the water / air level

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

No guarantee any submersible will ALWAYS be submerged, Murphy law always applies.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

Depends on the control system.

Like the OP says - all the other ones are like that so why just this one?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

Not sure why the Contractor would make such a statement as one can procure explosion proof submersible pumps.

However, you have not provided enough details on your application to understand it. What is the application, pump size, pumping conditions, chemicals, etc.

You should be aware that submersibles have higher maintenance requirements than other pump types.

 

[vjr0512]

Thanks for all the answers. These pumps are intended to be used for an effluent treatment plant in the chemically contaminated waste water collection pit.Originally these pits were not classified and contractor suggested to use the fully submersible pumps ( flyght / Xylem make). Now since these pits are classified for Zone 2, they say that they cannot get these pumps certified for the zone classification.

I can always ask for the evidence from the manufacturer for their inability to supply these pumps, but would like to get the opinion of the experts in this forum.

 

[Artisi]

The experts are the pump designers / manufacturers and testing authority, not consultants, and certainly not resident experts or end users etc.
Give the full spec. to the pump company/s for selection and recommendations.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[ScottyUK]

vjr0512,

KSB offer at least one submersible type for hazardous areas - the 'Amarex N' series. Sulzer offer the similar ABS series. The contractor either genuinely doesn't that know that these types exist, or the contractor doesn't want to admit that they exist because they are expensive.

 

[LittleInch]

vjr,

my point remains though which is that the pit itself might be classified zone 2, but surely this starts at the liquid level, being an atmospheric gas thing.

If your pumps are always below liquid level they are not "officially" in a zone 2 area??

A bit like this

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TenPenny]

It's not that uncommon to want hazardous zone submersibles, so I don't know why it's a big issue. Are all the players in this job working outside their comfort zones?

 

[bimr]

In addition, the pit should have been classified.

 

[ScottyUK]

LittleInch,

You're right - depending on the service the vapour space within the pit could easily be a Zone 0, but below the liquid level is non-hazardous as oxygen is excluded. The difficulty comes in the event of a pump-dry scenario which exposes the running pump to the vapour space.

There are two approaches - one being to ensure that a pump-dry condition absolutely can't occur, and the other being to certify the pump for occasional operation in a hazardous area under abnormal conditions. Using a non-certified submersible pump would require a high integrity safety system to trip power to the pump in the event of a pump-dry condition. Generally this system would need to be fully independent of the pump level controls, and fail safe. There's a good chance that a safety instrumented system of adequate integrity would cost more than the premium for a properly-certified motor.