High pressure in sand filter

Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
Yes I will show more pictures.
But
Something is definitely not right with that unit if the lid is popping off at only about 20-30 psi. Even on their website HERE they show a pressure gauge that goes up to 50 psi. You would never want it that high on purpose, but it should be able to retain the pressures you noted. There must be a restriction either in the filter or beyond. Something assembled wrong in the filter, or a closed/defective valves after the filter.

On a side note, @JamesW do you have experience with this make/model filter?
Hi,

You're pointed out a very very important thing (once again :)) and it's probably (not sure but probably) the solution :

I though that this filter hasn't air purge (because first, when I've checked the website to know which kind of gauge was needed - in cas the gauge was faulty - I was confused between air purge on the top close to the gauge (this model hasn't such air purge) and the real air purge (spare parts No 19 and 20).

With your link of astral's website it's very clear : this filter needs air purge (spare parts No 19 and 20).
So I checked my filter (easy because the lid is out after iit has exploded ...) and it appears the air purge has gone...

Why ? When the maintenance team checked system the first time (leak on the MPV) they opened the filter. And probably they took off the air purge and forgot to replace it.

I've ordered the spare parts, will be there in the next 2 or 3 days. and let you know.

Not sure 100% the solution is there, but I think a filter working without air purge might cause such problem.

I'll let you know as soon as possible if it works.

Thanks.
 
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Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
Can you show more pictures of everything?
Hi,
Attached photo of the top filter. Cannot see air purge. As I said replying to Texas splash, the problem could be caused by the lack of air purge. I've ordered and let you know.
Thanks.
 

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JamesW

TFP Expert
Mar 2, 2011
27,718
A lack of an air relief valve won't make the pressure any higher.

More air will make the explosion more dangerous due to compressed air expanding and causing parts to be ejected at high speed.

Have you contacted the manufacturer about this?

This is a dangerous situation that needs to be figured out before someone gets injured.
 

JamesW

TFP Expert
Mar 2, 2011
27,718
Admittedly the pump is 7 meters below the pool,
That's going to create an extra 10 psi just from the distance below the pool.

Is this a commercial pool?

What country are you in?

What is the horsepower of the pump?

How old is the filter?
 

Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45

A lack of an air relief valve won't make the pressure any higher.
Yes, you're right. Waiting delivery of the air purge in the next day, I checked again and the pipe is there, seems to be screwed in the bottom, even if the top of the pipe isn't not there.

So unfortunatly, the reason is elsewhere.

Have you contacted the manufacturer about this?
Yes, I've the same day you ask me to do. The main office seems to be in spain. But phone they look nice but not very interested in the case, seem to be on holiday. Only way to contact them by email, which I did. Waiting for reply.


Can you show more pictures of everything
I tried to be exhaustive. Please find attached some pictures of the whole systems and specifics areas. Water comes from the pool by 3 ways (vacuum, main drain and tank - means buffer tank for infinity pool) on the left hand side, goes to pump, check valve, MPV, filter and on the right hand side goes through the electrolyser before returning to the pool.

To answer your last questions,

I understand that 7 meters from the pool to the filter is going to create an extra 10 psi but before the problem of high pressure appears, the pressure gauge was at 0 when I closes the pump. Don't know if it is related.

Is this a commercial pool? No private one.

What country are you in? Thailand

What is the horsepower of the pump? 3HP

How old is the filter? 4 years old.

I hope the pictures attached and theses informations can help you to help me. I've just received the spare part (closing lid unit for the filter) but as I has been broken twice and you talked about the risk of explosion, I wonder if I will restart the system after replacing the new lid or if I'm goign to wait until we find a solution.

As in this country (which is nevertheless very nice), it is very difficult to make people understand that I want a reliable solution, I am really alone with this serious problem.
I do appreciate the help you can give me through to the TFP forum.
 

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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,433
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Stefany, maybe a silly question but ....... those two gray valves that are used before and after the salt generator, are they always on that position? I know the red handles everywhere are currently closed because your filter is broke, but those grey valves are partially closed as well. That would increase your filter pressure.
 

JamesW

TFP Expert
Mar 2, 2011
27,718
I understand that 7 meters from the pool to the filter is going to create an extra 10 psi
Before, you said that the equipment was 7 meters below the pool.

Is the equipment at the same elevation as the pool or 7 meters below the pool?

Why do you need a 3 hp pump?

Is it a variable speed pump?

If yes, what speed do you run the pump?

What is the pool size?
 

JamesW

TFP Expert
Mar 2, 2011
27,718
This looks like a commercial pool more than a residential pool.

In any case, the filter should not be used at flow rates above about 100 gpm.

A 3 HP pump is too big for the system and there is no reason to have that much power, flow or pressure.

The black ring in the below picture looks damaged and it should be replaced if it can be replaced.

1626533230569.png
I would recommend that the pump be replaced with a variable speed pump like the Pentair intelliflo and the flow dropped down to about 30 gpm unless you have a heater that requires more flow.

If you can’t get the current filter to work without exploding, I recommend a Pentair - Triton II - TR140 Sand Filter or a Pentair Clean and Clear Plus cartridge filter in 420 or 520 square feet.
 

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Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
Stefany, maybe a silly question but ....... those two gray valves that are used before and after the salt generator, are they always on that position? I know the red handles everywhere are currently closed because your filter is broke, but those grey valves are partially closed as well. That would increase your filter pressure.
yes those 2 gray valves are always in that position. Not exactly partially closed because in that position it means, 70% of the water flow goes through the SWG and 30% without. No water is stopped.
I checked before to by pass 100% the SWG, the filter pressure decreases just a little bit. And if 100% of the water goes through the SWG, filter pressure remains the same.
 

JamesW

TFP Expert
Mar 2, 2011
27,718
1626536099176.png




As you can see below, the pump is very strong and way too powerful for your filter.

You really do not need more than 1.0 hp.

You can replace the impeller and diffuser to make the pump less powerful.

53976-4008101 BX ( 0.75HP) CTX (1.0HP) Impeller.

53976-78720 Diffuser 0.5HP - 2.5HP

1626536521280.png
1626536677660.png
1626536740667.png
 

Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
Before, you said that the equipment was 7 meters below the pool.

Is the equipment at the same elevation as the pool or 7 meters below the pool?

Why do you need a 3 hp pump?

Is it a variable speed pump?

If yes, what speed do you run the pump?

What is the pool size?
Sorry this was a mistake. The equipment is 7 meters below the pool and not "from".

Pump : I don't know why the company installed a 3HP pump. When they installed all the equipment, honestly I didn't check anything, they told me "you need this" so I bought it without checking because I had to many things to check during the building of the house. I remember they told me you need a very strong equipment, even oversized, because the pool is very large and 7 meters above the ground floor where the equipment had been installed.
The pump is not a variable speed.

Pool size : Difficult to calculate exactly because it's a free form. When I refill the water I need about 200,000 liters (200 cubic meters). The whole surface area is about 300 sqm, 200 sqm with 1 meter depth, 50 sqm with 0.3 meter depth
 

JamesW

TFP Expert
Mar 2, 2011
27,718
7 meters above the ground floor where the equipment had been installed.
The distance below the pool should add about 10 psi to the filter but it does not require a bigger pump because the pressure is exactly offset by the pressure pushing into the suction.

I would downsize the impeller and diffuser to significantly decrease the flow and pressure.

I would go with a 53976-4008101 BX ( 0.75HP) CTX (1.0HP) Impeller or a 53976-4008102 BX ( 1.0HP) CTX (1.5HP) Impeller.
 

Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
It looks like the assembly is replaceable.

I would replace the part along with the other parts and lower the flow rate significantly.


View attachment 355887
View attachment 355888
Yes I didn't see it before, but I think at the begining the maintenance team does something ther (maybe replace the o'ring), and now it looks damaged. Easy to buy the spare part, not to install (I checked before trying to tight them, but the nuts are almost impossible to reach from above. No matter how I would manage). I will order it on monday.
 

Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
The distance below the pool should add about 10 psi to the filter but it does not require a bigger pump because the pressure is exactly offset by the pressure pushing into the suction.

I would downsize the impeller and diffuser to significantly decrease the flow and pressure.

I would go with a 53976-4008101 BX ( 0.75HP) CTX (1.0HP) Impeller or a 53976-4008102 BX ( 1.0HP) CTX (1.5HP) Impeller.
With all the information you give me, it seems obvious that I should have been more attentive to the technical characteristics of the equipment they offered me during construction. I've just learn a few days ago only that the pressure is offset by the pressure pushing into the suction line. So 4/5 years ago they could tell me anything.
Anyway, I fully understand the change of impeler and , I have already disassembled them to check that everything was clean. If I understood correctly, if I change impeler for the reference BX 0.75HP or BX 1.0HP, I also change the diffuser to downgrad it from 3HP to the model 05HP-2.5HP reference : 53976 78720 ?
 

JamesW

TFP Expert
Mar 2, 2011
27,718
If I understood correctly, if I change impeler for the reference BX 0.75HP or BX 1.0HP, I also change the diffuser to downgrad it from 3HP to the model 05HP-2.5HP reference : 53976 78720 ?
Yes, that is correct.
 

JamesW

TFP Expert
Mar 2, 2011
27,718
Also, get a new seal (53976-75508 Mechanical Seal 3/4”) and all new gaskets and O-rings.
 

Stefany

Member
Jun 29, 2021
24
Thailand
Pool Size
200000
Chlorine
Salt Water Generator
SWG Type
Astral Viron V45
Yes, that is correct.
thanks so lot

Just 1 more information : I hope that downgrading the impeler doesn't matter with this kind of pool (endless feature) which need water to overflow in a tank behind the pool.

And 1 last question : I understand everything about the "sizing" of all the equipments and I will do it following your recommendations. BUT, the high pressure problem began about 2 months ago. In your opinion could it have been caused by an unfavorable evolution of the badly dimensioned system or will it be necessary to look for another cause even after having changed impeler and diffuser?

Thanks for everything.
 

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