fire water pump having frequent strainer plugging , 3

[chammany]

i am having a bit of problem with suction strainer plugging very frequently ,
is there any solution to reduce the problem .
strainer is plugged with yellowish scale which can be removed by knocking or by brushing
give me some tips to improve the pump suction performance .

 

[ashtree]

Probably need a bit more information.
Info that might be useful
1) What is the water source from which you are pumping.
2) What size is the mesh on your suction strainer? What material is the strainer made of?
3) How long does it take for the suction strainer to plug?
4) Is the suction scale soluble in water , in acid , in ethanol?
5) What sort of flow rate?
6) What style pump?
7) What style fire system are you supplying.

I am sure someone else will chime in with other items.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[LittleInch]

Some pictures always help a lot as well.

but without any idea of what this "scale" is, or how it gets into your system, it's very difficult to provide any advice

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

 

[Artisi]

Back flush the strainer every week, see if that helps.

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.)

 

[chammany]

1) What is the water source from which you are pumping.

ans: water is pumping to the suction tank, from the desert field of Saudi Arabia by submersible pump
there is no water treatment or filtering before it pumping to the tank.
water is pumping directly from the field

2) What size is the mesh on your suction strainer? What material is the strainer made of?

ans: mesh size is about 1/8 inch (3mm) size round hole with cone shape , cone( sharp edge) is placed and facing against the flow
strainer material is stanless steel

3) How long does it take for the suction strainer to plug?

ans: every two week we have this problem ,
we know this is from the field water , but how to treat this water before it entering to the tank
is there any filtering system or chemical treatment required?

4) Is the suction scale soluble in water , in acid , in ethanol?

ans: the scale is soluble with water , but acid and ethanol I don't know , I will check it during the next frequency

5) What sort of flow rate?

ans: 6 inch and 150 rated suction flange.

6) What style pump?
ans: Worthington pump, LRG DOUBLE SUCTION SINGLE STAGE with discharge nozzile of 3 inch 300 rating

7) What style fire system are you supplying.
ans: closed loop system with a constant pressure of 120 psi.

 

[georgeverghese]

Source may be some heavily polluted river water - mining site further upstream ?

 

[LittleInch]

I can only assume here that you have a water well and you're lifting ground water from an acquifer.

It sounds like you have a scaling issue with some elements in the water.

You really need to get some samples and send them to a chemical treatment supplier for analysis and possible injection of chemical to prevent the scale from forming.

Otherwise, you could just accept it and get some better filters which either backwash, auto clean or use duplex filters and just clean them on a regular basis and fit differential pressure gauges / transmitters to tell you when it needs cleaning. "cone shaped" implies a simple strainer fitted between flanges which is difficult and time consuming to remove, clean and put back?

A fire water system should only be pumping occasionally to fill up your fire water tank so unless you're using this water as "utility" water, then it shouldn't be running continuously


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

 

[Artisi]

Why have a strainer - are there any solids in the supply from the wellpumps?
Have you noticed build up of this material within the 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.)

 

[bimr]

Strainers of that size are usually installed during the construction to prevent the pump from being damaged.

After construction is complete and the lines are flushed, the strainers are removed.

If you feel that the strainer is necessary, you should use a much larger mesh size as the mesh size that you are using is too small.

 

[georgeverghese]

Cant tell what this yellowish scale might be. Is the suction pipe made of copper nickel ? Cu - Ni corrosion product (which could occur in hot brackish water with salt content higher than in seawater) is usually yellowish green.

In any case, a conical strainer ( witch's hat) has little solids retaining capacity. Try switching out to a duplex basket strainer assembly, which has more solids retaining capacity that a conical or Y type strainer - this should keep you going for some time. Add on a manual backflush facility to this if you can afford the space and money.

 

[Artisi]

Probably no need for any strainer, OP has indicated that the water is pumped to a holding tank of some description (suction tank), sufficient to make sure the pump inlet pipework is positioned above the tank bottom and sized to reduce the inlet velocity.

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.)

 

[ashtree]

There is a multitude of issues here but i think the biggest question is: Why is a fire pump being operated sufficiently to block a strainer every two weeks. Either the water is shockingly dirty or the fire system is being used for utility supply. Perhaps they have a lot of fires or fire practice.

If the system is being used for utility supply then something different needs to be done and a bigger capacity , self cleaning etc filter needs to be installed.

If it is just a straight fire system with the pump simply being used for occasional purposes then maybe no strainer is required like is suggested above.

chammany

How much water do you pump in two weeks between filter cleans. If you don't have a flow meter can you say how many hours the pump runs between cleans. What are you using the water for?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[Artisi]

After many questions from a multitude of members, the most important one hasn't really been fully addressed.
So here goes, is there any evidence of solids in the pumped water, if there were it would be evident at the strainer.
If no solids, simply removed the strainer, no more clogging from the unknown "sludge" - problem solved.

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.)

 

[JJPellin]

I agree with Artisi. I would look very seriously at the option of removing the strainer. If it is not catching solids that would be too large to pass through the pump, then it hurting you more than it is helping you. I don't like permanently installed suction strainers.

Johnny Pellin

 

[TugboatEng]

Cone shaped strainer? Does it mount between two flanges? That sounds a lot like a commissioning strainer and should be removed after the initial run.