Gas Chlorination Booster Pump Selection

[jartgo]

I'm working on a booster pump for a gas chlorine system. The client is determined to include gas chlorine in lieu of hypochlorite, so that issue is settled. I'm having some reservation with settling on a booster pump for the ejector. The ejector to be provided by the supplier is a REGAL 13A which manufacturers literature states a requirement of 132PSI and 5.1 GPM. The 13A is rated for 10PPD. My design feed rate is 5 PPD. This seems logical.

My well pump system will be approximately 90 PSI at the chlorination point. Thus, I have considered the following calculation: 132 PSI (required) - 90 PSI (available) + 5 PSI (assumed booster pump losses) = 47PSI = 109 Ft TDH

So, I'm looking for a booster pump to provide something close to 5GPM at 110 Ft TDH. I've been looking at the Franklin Electric BT4, but the smallest pump (5gpm) that they make is 1 / 3 HP and in moves 7 gpm at 140 at the far right point on the curve.

I guess I feel like it's fairly unrealistic to think I'll find a pump that meets my conditions exactly and I'm not sure which direction to go from there. Do I get the 1/ 3 HP BT4 and try to size the discharge piping to impose additional friction losses (this seems illogical in that it would require friction of about 200 feet of ½" SCH80 pvc) or perhaps just close a discharge valve to create the loss? How much leeway do I have based on the requirements listed on the ejector literature? If I can't meet it exactly, which way should I lean? Should I consider that the published literature is rated for 10PPD and my feed rate is 5 PPD? Any suggestions/direction would be appreciated.

 

[bimr]

Chlorine gas is never injected under pressure. You normally would have a vacuum regulator mounted on the CL2 cylinder. The gas is fed from the regulator into an ejector installed on the bypass water line.

http://www.regalchlorinators.com/page15/page15.html

You should furnish the bypass water line with a booster pump. Webtrol makes these booster pumps. The ejector is installed on the discharge side of the booster pump. Select the pump that meets the chlorine ejector requirements.

Don't use the Franklin Electric BT4, it is cast iron, use an all stainless pump.

 

[jartgo]

Maybe I didn't do a well enough job describing my setup, but it is as you describe. The BT4 is also available in stainless. I will certainly look at webtrol.

I think my curiosity still stands with the question previously asked. Perhaps it will be more clear once I look at the webtrol curves.

 

[bimr]

Maybe this link will answer your questions:

http://www.hydroinstruments.com/files/Booster Pump and Ejector Guide.pdf

 

[SteveWag]

I am not sure what the curve for the Franklin pump looks like. I have always used a turbine style pump for chlorine feed water applications. An APCO/Aurora/Pentair E4 will supply 5 GPM at 115 Ft and 1750 RPM. Look at some small turbine pump curves. The pump need not be stainless unless the supply water has a high concentration of bad stuff. As this is a booster application I guess not. REAGLE is a very nice company to work with and the 13A should be fine selection. Your piping should look like Fig 1 in the REAGLE Bulletin No. 1002, less the well pump, meter and check.
Steve

 

[semo]

Your pump doesn't have to match the 5 gpm at 109 ft specifically. If your flow rate is higher, it will create a larger vacuum through the venturi which will be better for the pull of chlorine gas.

They should also have various sized ejectors (venturis) for various flows and pressures. The interior nozzle sizes will vary and require different flows.

I would check with Regal and have them help you if you haven't done it before.