Repair of C-1100-Sep Series Hayward DE separation tank

[mitzie]

This is a solution to the DE separation tank leak from cracks in the shell that TFP website users have reported in the past. This occurs near the top of the tank when the black ledger support internal ring splits and lets the DE filter bag be pushed down causing its top sealing ring to expand the shell as it descends into the tapered body internally. The tank is subject to a lot of pressure over a small surface area during the backwash process and the bag descending past a broken support ring causes further expansion pressure from the tank inside due to its tapered construction.
The repair is to use epoxy glue into the crack to seal it and use a series of eight 10 inch worm gear band clamps you can get on Amazon for $14 to reinforce the wall over the outside of the tank to give it the needed support. You still need epoxy glue to put back the ledger black inner ring that supports the separation bag top ring and it will stay there once you band clamp the outside of the tank. The steel bands on the outside of the tank act a safety sleeve to make this repair safe and strong.
This repair works very well and will save you the $600 for a new expansion tank which is still made from the same plastic. Due to its limited production numbers the cost of a new DE separation tank remains high. DE is a very messy and noticeable contaminate when blasted to the ground or street so it is best to contain and dispose of it properly which is what the DE separation tank does. If it would only cost a bit less more pool users would use it and its production numbers increase thereby reducing its market cost and save the environment at the same time.
The stainless steel Pentair separation tank is stronger than the plastic but it is off the market. There are only two separation tanks available currently on the market-- one from Pentair and one from Hayward and both are plastic.

 

[ajw22]

Thanks for the description of the fix.

Any chance we can see some pics of what you did?

 

[JamesW]

A pressure vessel should never be repaired.

You can get dewatering bags pretty cheap if you want to catch the DE.

DeWatering Bags for Oil and Sediment - New Pig

Order our DeWatering Bag. High surface area designs remove oil and sediment from higher-volume pumping outflows. Buy at newpig.com.

www.newpig.com

Mutual Industries 5 ft. x 6 ft. Black Non-Woven Dewatering Filter Bag 15925-500 - The Home Depot

Sediment Filter Bags, also known as Dirt Bags or Filter Pump Bags, are designed to control and filter silt and sediment had laden water during dewatering activities. Filter Bags are constructed of non-woven

www.homedepot.com

 

[JamesW]

 

[mitzie]

All boilers by law must have automatic pressure relief valves and expansion tanks rated for 30 psi so water pressure and heated expansion doesn't cause explosion or damage and these boilers are made from cast iron or steel vessels. Here we have plastic polymer that is not with a dense core and aged brittle by sunlight without any pressure relief valves for safety and no any expansion tanks even when a pool heater is used. The videos show the pressure gauge lens is frosted from age so no one can see the pressures. Aging plastic will eventually crack and pressure changes and sunlight hasten this process. For safety I always use a pressure relief valve set at 30 psi which is the maximum pressure these plastic tanks can safely handle. The true operating pressures of a pool system are 15 to 20 psi with shutdown being recommended at 25 to 30 psi so an automatic pressure relief valve at 30 psi will provide automatic safety. The explosions shown in the videos you show are occurring at 50 psi or more. At 20 psi with a system failure due to plastic fatigue and cracking will not give you such explosions seen in these videos. Clamping mechanisms should be inspected and replaced if fatigue or corrosion is present. Fiberglass with glass mat reinforcement and UV inhibitors gel coat or steel or aluminum used to build tanks is a much safer choice that plastic polymer material. Follow the aviation materials design using fiberglass or aluminum for safe material choices. You need to avoid being near or on top of a pressurized tank with the motor running. All plastic left in sunlight for many years will degrade so when it starts cracking under pressure changes or flexing that material has finished its life span. Bridges, airplanes, tanks, tower steel building, car frames supports all have been reported with cracks and failures so all need inspection repair and replacement. This weak plastic tank construction is flawed from the day one of its creation and inception and to subject it to high pressures without safety pressure relief devices is just asking for trouble.
My repair described should condemn the material as end of life but it was obvious on inspection that it was a seam and that makes it a manufacture defect from day one. The steel cladding of the repair is what makes it safe because it acts as a safety cage. I will send pictures so you can see the safety features of its design. Ideally the whole filter system should be replaced at its end of life before burst fatigue is seen so tell me who will do this practically? Boilers and water heaters have end of life expiration dates but pool equipment never heard of such a thing.
Keep pressures low and use automatic pressure relief valves and no one will get hurt.

 

[JamesW]

The explosions shown in the videos you show are occurring at 50 psi or more.

Residential pool pumps cannot get to 50 psi.

At 20 psi with a system failure due to plastic fatigue and cracking will not give you such explosions seen in these videos.

20 psi of compressed air can definitely give you the explosions seen in the videos.

Once the filter is compromised, it should be taken out of service immediately and it cannot be fixed in any way that will make it safe again.

 

[JamesW]

At 20 psi, you have about 2.4 times more air in the filter than you have at 0 pressure (gauge pressure).

0 gauge pressure equals 1 atm.

So, the air can explosively decompress and send the top flying with enough force to seriously injure or kill someone.

The explosions seen in the videos are normal residential pool systems at pressures that normal residential pool pumps produce.

 

[mitzie]

Here are the pictures ajw22 asked for. The repaired area is encased in a steel cage stronger than it was new. JamesW point is that it can rupture elsewhere below the repair so that will require the whole tank be encased in those band clamps to make a complete safety cage. The reality is the design is completely flawed from the time its new because plastic polymer is not meant for hydraulic pressures and this design would be safer if made out of steel or aluminum or true fiberglass with woven roving and epoxy resin that is pressure rated. Cast plastic is notorious for cracking even when new and especially if aged by the sun. Maybe JamesW can advise how to determine end of life of plastic tanks and filters for replacement or disposal before cracks and separations occur. These items are very costly so I would hope consumers could get at least ten years of use safely even in bright high sun climates that would make plastic brittle. Since you cannot see or feel compromised plastic and complex imaging is too costly what I do is the tap hammer test. If you hit aged plastic with a hammer and it breaks like glass you will have to throw the whole thing away.

 

[JamesW]

Maybe JamesW can advise how to determine end of life of plastic tanks and filters for replacement or disposal before cracks and separations occur.

Maybe an MRI, Cat scan, X-rays, ultrasound or other scanning technique.

If the plastic is cracked or brittle, then do not take a risk, just get rid of it.

Usually, the plastic will change color and begin to get very fine crazing cracks.

It partially depends on the pressure.

The more pressure the tank is under, the more caution you need to exercise.

The unreinforced plastic with a single nut holding things together is not a good design especially for higher pressures.

People should also never put their face or body directly over any filter if the filter is pressurized.

 

[mitzie]

Open the link below and see the same product with the same part number only one is made very strong long lived fiberglass reinforced wall and double the price and the other is very weak short lived polymer plastic only polypropylene wall and half the price. See this Amazon link.

Amazon.com

New plastic polymer $569. Pentair EC-160354 Filter Pump Cartridge Assembly

Old fiberglass reinforced $1,120. Pentair 160354 Clean & Clear RP Fiberglass Reinforced Polypropylene Tank Cartridge Pool Filter, 100 Square Feet, 100 GPM (Residential)

I also have older Hayward filter tanks that are also fiberglass with glass matt and glass fabric roving with gel coat with epoxy resin and the newer Hayward tanks made from polypropylene cast plastic polymer. Older Pentair tanks were also made from stainless steel. The picture below shows a cast polypropylene Hayward filter tank reinforced with stainless steel band clamps which is not recommended on an old tank but would be ok on a brand new tank to make it stronger and last longer if you can't get the older strpnger version for double the price. .