NOSHOK KING-GAGE 5900, Operation & Calibration Manual

Page: 8 / 12

page 8
Model 5900 D/P Module EX-1710-1
P 1
P
2
Sensor
Surface of Liquid
E S
High
Pressure
P
1
+ P
2
Low
Pressure
P
2
P
1
+ P
2
(P
1
+ P
2
) - P
2
= P
1
Gauge
Air Signal
S E
P
1
P
2
Sensor
Surface of Liquid
E
S
High
Pressure
P
1
+ P
2
Low
Pressure
P
2
P
1
+ P
2
(P
1
+ P
2
) - P
2
= P
1
Gauge
Air Signal
S E
Range Less Than 3.00 PSID
When the nominal 5 psid transmitter is used on an
application whose maximum pressure is less than 3.00 psid,
the full calculated range output will be less than 20 mA.
To determine the actual milliamp output of the transmitter
when the maximum applied pressure is below the lower
span limit, use the following formula:
(16 × Calculated PSID)
3.0
+ 4 = mA Output
Note
The above formula may also be used for other nominal
range transmitters if maximum applied pressure will be
less than the adjustment range allows. Merely divide by
the lower span limit psid value (listed above) in place of
the “3.0” shown in the formula.
Low Pressure Input
Internal Tank Pressure or Vacuum
In a closed, pressurized or evacuated tank, it is necessary to
measure differential pressure. This is achieved by subtracting
the internal pressure condition of the tank above the surface
of the liquid from the total pressure sensed at the bottom
of the tank. When the low pressure is applied to one side
of the transmitter sensing element and the high pressure to
the other side, the internal tank pressure above the liquid
(low pressure) is balanced across the sensing element. This
is also referred to as being “equalized” (which is why we
designate the low pressure connection as “E”).
CAUTION: While the internal pressure above the liquid is
not a factor in determining range (span), there may be
instances where the sum of the liquid and internal pressure
exceeds the 150 psi burst pressure rating of the transmitter.
Also, do not subtract pressure when a vacuum condition
is present within the tank (since loss of vacuum would be
seen as an increase at the high pressure connection of the
transmitter).
ON
1 2 3 4
ON
1 2 3 4
ON
1 2 3 4
ON
1 2 3 4
ON
1 2 3 4
Decrease
mA
Increase
mA
ON
1 2 3 4
ON
1 2 3 4
ON
1 2 3 4
Coarse Setting Procedure
: The number of switches in
the ON position will increase the milliamp value as each
switch controls an identical fixed resistor. To increase
milliamp output, place additional switches into the ON
position. To decrease milliamp output, move switches
to the off position.
1 2
3 4
ON
17.002
Meter
DIP Switch
1 2
3 4
ON
19.970
Meter
DIP Switch
DIP Switch—Coarse Adjustment
Coarse Range Setting—Alternate Version
Previous versions of the D/P transmitter employ similar DIP
switches, but only offer 5 increments of coarse adjustment.
With these versions, the span potentiometer offers greater
range of adjustment.