Chemglass AF-0304 - Manual (Page 23)

21
Our standard gauges are shipped without a resistor in the
R-5 position in the high relay circuit and without a resistor
in the R-13 position in the low relay circuit. This produces
about ± 1 digit hysteresis.
Installing resistor values as shown in the table will
increase the hysteresis. Keep in mind that these are
digits, not mTorr, Torr, or any other pressure unit. ±10
digits is ±10 mTorr on a 2000 mTorr full scale instrument.
On an instrument with full scale of 20.00 Torr ± 10 digits
is +/-.10 Torr. The set point is always in the middle of the
hysteresis band. For example, a 20.00 Torr gauge with a
set point of 15.00 Torr and a hysteresis of ± 10 digits
would cause the relay to change state at 15.10 Torr and
14.90 Torr.
2 megohm ± 2 digits
1 megohm ± 3 digits
700 K ohm ± 5 digits
500 K ohm ± 7 digits
365 K ohm ± 10 digits
250 K ohm ± 15 digits
200 K ohm ± 20 digits
160 K ohm ± 50 digits
80 K ohm ± 100 digits
Resistance
Value
Hysteresis
Band Width
R-5 and/or R-13 Resistors