BOREAL LASER GasFinder FC, Руководство по эксплуатации

Страница: 32 / 88

4.6
Boreal Laser Inc. GasFinderFCr Operation Manual — Data I/O July 17th 2017
Low Limit ppmm High Limit
ppmm
mA
20
4
12
1.0
3.6
Status Indicators
2.2
Graph showing the relationship between ppmm and the 4-20mA output.
4-20mA details
Note that in a dual gas system, Gas B does not have a 4-20mA output.
4 mA is equivalent to the lowest value of gas programmed, usually 0 ppmm. •
> 4mA and < 20mA varies proportionately to the gas concentration. •
20mA is equivalent to the maximum ppmm or greater. •
If the D istributed C ontrol S ystem(DCS) is capable of a full 0 - 20mA resolution, the following
values are confi gured:
3.6mA indicates a system fault •
1.0mA indicates a Low Light condition*. •
These values can be changed at the factory to suit particular needs.
*Note that where loop isolators are used the Low Light condition will be 2.2mA as the isolators
require 2.2mA to operate.
This relationship is illustrated by the following diagram.