Here are a few pro's and con's for a lined carbon steel softener option and a composite fiberglass softener system.
Advantages of carbon steel lined softener system:
- Lined carbon steel system has top man ways and side wall handholes. Having these access points to get to the resin bed and underdrain hub and lateral can be extremely helpful when changing the resin. Changing the resin can take place every 3-8 years and is contingent on chlorine levels in raw water.
- If the underdrain fails the lined carbon steel tank would stay in place with face piping left in-tact. The repairs could be accomplished from the side wall handholes.
- Lined carbon steel tank can resist being damaged with a passing forklift or other moving equipment
- If power fails and water pressure is still available, the unit can be generated manually. This is done by manually turning the pilot stager to each service cycle for the specified time in the step.
- If a temporary vacuum was ever introduced on a lined carbon steel tank it would likely not have any damages to the liner or tank.
- Higher flow rates can be achieved with lower pressure drops on 2" inlet/outlet 30" diameter carbon steel softener system versus a fiberglass system same tank diameter using a Fleck 2" 2900 valve
Disadvantages of a carbon steel lined system:
- Lined carbon steel pressure vessel softeners are more costly and more expensive to assemble
- Longer lead times associated with these systems (4-8 weeks)
- Lined carbon steel tanks make for a lot of condensation and unlike fiberglass tanks aren't as resistant to corrosion even with a primed and painted exterior
- Longer Lead Time to procure system components and to build the softener system
Advantages of a composite fiberglass tank softener system:
- Lower cost materials to build the softener system
- A spare identical multi-port valve and control can be kept as a complete spare and be changed out in kind.
- Shorter lead time. valves and composite fiberglass tanks are readily available. (1 - 3 weeks)
- Pressure vessel is resistant to corrosion from tank condensation
Disadvantages of a composite fiberglass tank softener system:
- Can't withstand a vacuum being drawn on the tank. A lined composite fiberglass vessel under a vacuum would likely have a polyethylene liner failure. For this reason a vacuum breaker should be installed in a tee on the inlet water piping.
- The piping needs to be supported by framework and the connections to the tank need to be flexible.
- On a fiberglass tank softener system if the hub and lateral needs to be changed the tank would have to be lowered down to the ground in order to reach in and replace the hub and lateral
- In order to change resin, the unions on the multi-port valve inlet, outlet and drain would need to be broken and the multi-port valve must be to unthreaded from the top of the tank. If this is done multiple times over a short period of time, the tank threads are prone to leaking
- If seismic specifications are needed on the pressure vessels, fiberglass tanks shouldn't be selected
- If there is an electrical power failure the multi-port valve is not operable and the unit can't be regenerated
- The commerically available controllers that are available with multi-port valve softeners are local only and integration with a PLC is not possible in most cases
Posted on October 4, 2011 by Tom Dupnik | Tags: FRP Tank
, Industrial Water Softener
, Ion Exchange Resin
, Pressure Vessels
, Stainless Steel Tank