Selection of Chlorinator system for deep well water supply 1

[RichieD]

I need some help from persons with experience with selection of chlorinators on the market. I see proposals for ORP system, Regal -vacuum chlorine unit, Chemtrol Chlorine/Ph Controller complete with real time sensors etc. What is the best value for money in a practical potable water system for a large office complex. 20,000 gal/day extraction rate of 50gpm and 3-4days tank storage. I don't want to reinvent the wheel and be dazzled with the brilliance of claims and highly differential cost.

 

[cub3bead]

If you just want to chlorinate and you want it simple a tablet feeder is the easiest. Look at:

http://www.ppg.com/chm_calhypo/equip.htm

Hope this helps.

 

[semo]

There is a lot of research you can do in this forum on Chlorination.

In my opinion, for such a small system, the vacuum (gas) chlorinator is overkill. I would look at a liquid chlorine source (calcium/sodium hypochlorite) with a small diaphram pump.

With 20,000 gallons per day, assuming you will be dosing at 1.5 mg/l (you will have to have a min. 1 mg/l residual in your water) you will only use about 0.25 lb per day of chlorine. A 150 lb cylinder (gaseous system), your source will last 600 days, almost 2 years.

A liquid system will (using sodium hypochlorite - 12% CL) you will use about 0.25 gal/day. You can purchase this in smaller containers to keep the storage time down (which you want to do with liquid systems). You can even purchase some bleaches as your source. This type of system can be very simple with a small inexpensive diaphram pump (for a few hundred dollars) connected to run when your well runs.

Just my 2 cents.

 

[sbush]

Cub3bead and Semo have each made excellent suggestions. I can only add few additional comments:

1. Take a look at the water delivery system and the point of chlorine injection. If the flow rate will be constant and repeatable with every cycle, then you can set up the chlorinator dosage by manually adjusting the metering pump speed and/or stroke controls until the desired chlorine residual is acheived at the sample point. However, if the flow rate will be variable, such as when multiple pumps with different capacities are involved or variable speed motors are used, or flow is by gravity from a secondary storage tank with variable head conditions; then the chlorinator should be equipped with a flow-pacing or flow-proportioning controller that operates in conjuction with a water meter signal to vary the chlorine metering pump feed rate according to the operating conditions. LMI, Pulsafeeder, and PPG Accu-Tab make excellent feeders and controllers for smaller water systems like yours.

2. Based on the number of people that could be onsite at a given time, your facility could possibly qualify as a small public or community water system. If so, there are certain requirements that you must follow in order to meet certain State guidelines. For instance, you may be required to monitor and record the free chlorine residuals on a continuous basis. If this is the case, there are several chlorine analyzers and chart recorders on the market. The most widely used brand of chlorine analyzer is the Model CL-17 made by Hach and the most common circular chart recorder is the Model DR4300 made by Honeywell. Both are reliable and reasonably priced.

3. In some applications, the chlorine demand can vary widely due to transient constituents in the water supply that consume free chlorine. The most troublesome of these transients is hydrogen sulfide gas. With hydrogen sulfide present, it becomes very difficult to maintain a relatively constant free chlorine residual. In these cases, an ORP or chlorine residual analyzer can be incorporated in the control system to automatically proportion the chlorine dosage based upon the chlorine demand in the raw water. Again, LMI, Pulsafeeder, and PPG Accu-Tab offer excellent controllers for this purpose, and the Hach CL-17 analyzer is a good choice for the sensor to the controller.

4. In some cases, where you have variable flow and variable chlorine demand, there is a control option known as the "compound loop". This method involves a water meter signal and a signal from a chlorine analyzer or ORP analyzer to control and maintain a chlorine residual setpoint.

5. Finally, systems that pump intermittently are subject to formation of chlorine gas in the lines which causes the metering pump to lose prime. If your system won't be running all the time, for instance on Saturdays and Sundays when the offices are normally closed, then I would specify a metering pump that is fitted with a de-gassing valve specifically designed for chlorine gas. LMI and Pulsafeeder offer one, and PPG Accu-Tab does not form the gas. Additionally, the room in which the chlorinator is located and chlorine is stored must be well ventilated. Particularly when liquid chlorine (bleach) is used because routine chlorine spills will form low level chlorine gas in the air that, although not harmful to humans, can cause rapid corrosion of metallic surfaces in the room.

You are wise, not to purchase any more than you absolutely need. The more complex the system, the more complex the headaches.

If you haven't already done so, you might check with your regional public drinking water permiting authority to see what applications and submittals are required for obtaining the necessary permits for your facility. Also, let them know what treatment equipment you're thinking of submitting and see if they have any objections, comments or suggestions.

S. Bush

http://www.water-eg.com

 

[Tonka73]

Rich

Real big subject mate in my opion hypo dosing would suit you best. Points to remember are hypo will "gas off" so keep it as cool as possible (around 15 degrees C is good). Also self bleeding dosing pumps (see Prominent pumps) these work really well. But there are loads of alternatives so look around.

You could try Chlorine dioxide which would maintain a residual for longer.

Hope this helps

 

[h2woah]

One more thing to think about, chlorine will dissasociate in water depending on the pH, this is why you maybe got a quote for a pH monitor. The higher the pH, the less "useful" chlorine you will have

I would always go with chlorine dioxide, dosed on the incoming into the building. This means you get the whole system, not just the tank fed