Tomar TV-6000, Owner'S Manual

CHEMICAL INJECTION RATE CALCULATION

First it is necessary to determine the Feed Flow rate to the RO system.  This is the product flow rate
which the RO will produce, divided by the overall % recovery:

The chemical injection pump performance is determined by by rate and stroke settings.

For example, say the RO is designed to produce 10,000 gpd and it will be set to operate with or
without re-circulation at 60% recovery:

The Feed Flow rate is 10,000/0.60=16,667 gpd.

A good rule of thumb is to inject anti-scalant at a rate of 3 to 5 ppm.  For our sample calculation we
will use 5 ppm.

The required chemical injection pump flow rate is 16,667*5/1,000,000=0.083 gpd.  This assumes
the use of undiluted anti-scalant solution.

The smallest pump has a range of 0.06 to 6.0 gpd.  Our required injection rate is right at the bottom
of the pump range.  It is best to run the injection pump not lower than about 5% of maximum, for this
pump about 0.3 gpd.  Also, the higher the pump rate the more even the injection flow rate to the feed
stream will be.

The anti-scalant can be diluted, but not to a lower concentration than 15%.  For our example we will
use 20%.  Our solution tank has a 15 gallon capacity.  We will plan on putting in 12 gallons total.  The
dilution mixture will be 12*0.20=2.4 gallons of anti-scalant with 12-2.4= 9.6 gallons of water.  This is
2.4/12=20%.

Dilution should always be with RO product water however, water bottled for drinking is adequate.

Now for pump injection rate settings.  The pump has adjustments for rate and stroke length.  Both
scales are in %.

The final pump setting will be for the 0.083 gpd anti-scalant corrected for the 20% dilution.  Pump
flow rate is 0.083/0.2=0.42 gpd.

Having the rate higher than the stroke will give a more even injection flow to the feed flow.

To judge where to start we see the 0.42/6.0=0.07 or 7 % of the pump maximum output.

We select a 20% setting for the stroke, which gives a pump flow of 6.0*0.2=1.2 gpd.

The rate setting then, is 0.42/1.2=0.35 or 35%.

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