Dealer Bulletin from Norvin Pellerin: B22DB94041 August 15, 1994

SUBJECT: SHORT DURATION CHEMICAL INJECTION TIMES DON'T WORK!

Gentleman:

It has recently come to our attention that some chemical vendors are commanding our microprocessor to signal short injection times - in the order of 2 to 3 seconds. Such SHORT INJECTION TIMES SIMPLY DO NOT WORK.

INJECTION TIMES OF LESS THAN 10 SECONDS WILL NOT PRODUCE CONSISTENT
CHEMICAL DOSING!

The reason for the above includes (but are not limited to) the following:

1. Chemical injection times in microprocessors are programmable in seconds. This means a 3 second injection can only be adjusted a minimum of plus or minus 1 second - thus modifying the quantities injected a minimum of plus or minus ONE THIRD! This is simply not precise enough. (Even the quantity delivered during a 10 second injection can only be adjusted a minimum of plus or minus 10%.)

2. It takes a certain finite time for any injection system to react - thus any delay or "dead time" in a 3 second injection will result in a HIGH PERCENTAGE ERROR. For example, in a 3 second injection, a total of only