Pressure issues...best location for new pressure tanks

[jimtheengineer10]

A client owns a mobile home park (75 homes) that is having some pressure issues. We are in the process of designing an entire new system but they want to fix their existing pressure problems before winter hits.

There is an on-site well that feeds an approximate 630 gallon metal storage/contact tank. The tank then discharge through a 4" pipe through the floor out to the homes. They are having pressure issues so they keep pumping air into the storage/contact tank. I am proposing three new 119 gallon pressure tanks to be installed.

I have met with a couple contractors who install these systems quite a bit and am getting different opinions. One says the three new 119 gallon pressure tanks should be installed before the contact tank and the other says they should be installed after.

Should the pressure tanks be installed before or after the contact/pressure tank?

 

[BigInch]

Why not ask each one why they prefer one location over the other, then we'll discuss that here.

 

[itsmoked]

Ditch the problematic pressure tanks for a supply that big and just use a VFD pressure package. It will perform far better and probably not even cost as much.

One example of many offerings

Keith Cress
kcress -

http://www.flaminsystems.com

 

[bimr]

Few questions:

Is the "630 gallon metal storage/contact tank" a pressure tank?

What is the capacity of the well pump?

Is there a booster pump after the "630 gallon metal storage/contact tank"?

Are you doing any water treatment?

Why don't you post a simple flow diagram?

 

[Artisi]

look up Grundfos " water pressure systems"

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.)

 

[hydrae]

The typical pressure tank also has the pressure switch to control the pump, you do not want a valve between the well pump and pressure switch unless you take precautions to prevent it be being closed and dead heading the pump for an unlimited time.

I assume you have contact tanks for Iron or Manganese removal treatment, but you do not mention a filter or softener for such treatment, so that, may not be the case.

Typically I see the pressure tanks first, but if the containment can precipitate inside the pressure tanks and is of high enough concentration this can lead to early failure of the pressure tanks. So in that case do the CT tank first, with precautions for a dead headed pump such as a relief valve before any other valve.

If you do not have Iron or Manganese, then I assume the storage tank was just a large pressure tank in which case, it is not needed with the installation of the new 119 gallon pressure tanks. By the way, if the existing tank was used as a pressure tank, then it should have an ASME boiler stamp on it (which also requires annual inspections). There is an exclusion for water pump pressure tanks below 120 gallons, hence the 119 gallon size. If there is no stamp do not add air to that tank just replace it with the 3 new pressure tanks.

Hydrae

 

[jimtheengineer10]

The system is an existing system that has been in place for a long time. I am in the process of designing a new system for the entire park. They are just trying to fix their pressure issues for the winter and then will build new in the spring.

It is a chlorine injection system.
No booster pumps
No water softener, iron or manganese removal

I have attached a schematic.

Should the pressure tanks go before or after the contact tank?

 

[hydrae]

I would go between Chlorine injection point and contact time tank.
Any earlier in the process requires rework of the Chlorine system for correct dosing.
After the tank and before the valves is OK but do not put them after the valves.

Hydrae

 

[bimr]

From what you are saying, the contact tank is a full tank, not a pressure tank. For that reason, the contact time is fixed by the tank volume. Sizing is based on the site restrictions, available pumping rate and a minimum required chlorine contact time.

Putting the pressure tanks after the contact will maintain the contact time.

If this is an Air-over-Water Pressure Tank, it does not matter where the pressure tanks are located.

http://www.ruralwaterresources.com/...enance-best-practices/pressure-tank-settings/