Select-382 Split Tandem Doser

This version of the 380 doser allows for two different products to be pumped at differing ratios. One of the pumps can be slowed so as to act at a smaller dosing ratio compared with the other.

For example, if you have two products to dose, at slightly different ratios, you can slow the right hand pump (under Options on-screen) to anything between 20% and 100% of the dose rate of the left hand pump.

Select-382 Split Tandem Doser

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Frequently Asked Questions

Q. How many ratios are possible?

Each Select doser is set up to receive signals from 7 flow sensors. Each of the sensors has 15 choices of ratio. These ratios can be anything from 1 : 20 to 1 : 1,000,000, although in practice the finest ratio used is 1 : 25,000 for hydrogen peroxide dosing.

Q. What size stock solution do I need?

The Dosatron type of doser requires you to make up a stock solution to suit the doser.

We have designed the Select doser so that you can dose product from the original container at the correct ratio without having to mix up stock solutions. You are therefore avoiding dosing inaccuracies and also avoiding coming into contact with (sometimes) aggressive products.

Q. How do I get rid of air locks?

This problem does not exist with the Select doser. The pump can move air as well as liquid. No more downtime using a syringe to suck out air locks!

Q. Can I run the Select doser from a battery?

You can. This is particularly useful when the Select doser needs to be used in a field situation (pheasants, free range pigs etc.).

A 12V leisure battery charged from a solar panel is also perfectly possible.

Q. Will the Select doser work connected to a water meter?

As long as we know how many pulses we get per litre (or gallon) we can connect to any water meter. We generally supply turbine flow sensors with our dosers as these are lighter for transport and are generally more accurate at low flows.

Q. Why are there different tubes to use with the Select doser?

If we used one large pump tube for all dosing ratios, at very fine ratios and very low water flows it might be several minutes before the doser was able to turn to inject product. Although this would still be accurate overall, folks prefer to see the doser operating more frequently with a smaller tube fitted.

Q. What if the ratio I want is not being offered on the screen?

Let us know. We can send you a new Eprom computer chip containing all of the normal ratios plus the one you need.

Q. Why do you use peristaltic pumps?

There are several reasons. With the dosed product kept inside the pump tube, even strongly corrosive liquids don't harm the pump, and there are no product residues in the pump to contaminate the dosed product. A win win.

Servicing of both diaphragm pumps and the Dosatron type doser can be fiddly and time consuming. Changing a pump tube in the Select doser takes around 23 seconds. This effectively services the doser.

The Select doser does not suffer from air locks. a huge advantage when dosing products that can generate gas bubbles.

Q. How long does a pump tube last?

It all depends on four things - the water line pressure that you are dosing into, the product being dosed, the condition of the rollers and the number of times the rotor squeezes the tube.

Choosing the correct ratio to dose the original concentrated product will save the tube being worn by pumping excess water from a stock solution. And - change the pump tube regularly to avoid it splitting. Leaked product can damage the rollers.

Q. Can I pump anything with a Select doser?

Almost anything. If you try to pump highly concentrated formic acid you will be out of luck. Nothing can withstand that!

Q. How do I calculate a dosing ratio?

Firstly - make sure that everything is in the same units.

An example:
A product has to be dosed at 5ml per litre. A litre is 1000ml. So the ratio is 1000 divided by 5 = 200. The dosing ratio that you need to choose on the Select-doser screen is 1 : 200

Q. Aren't diaphragm pumps better?

Diaphragm pumps can certainly pump at a higher pressure than a Select doser, but that is pretty much the only advantage.

99% of the time there is a low pressure point on a water line to dose into. Having actual dosing ratios (and flow data) shown on-screen on a Select doser, having superb accuracy of dosing and not suffering from airlocks all count towards the Select doser being a superior choice.

Q. What is the warranty period of a Select Doser?

Each Select Doser has a 1 year manufacturing warranty.
For full terms and conditions, please see the link at the bottom of the page.