168, 168H, and 68 Series
2
Table 1. Specifications
Maximum Allowable Pressures
Diaphragm
168 Series: 100 psi (6.9 bar)
168H Series: 150 psi (10.3 bar)
Body: See table 2
Operative Temperature Limits
(1)
–10 to +150
F (–23.3 to 66
C)
Port Diameter
3/32 in. (2.4 mm)
Flow Coefficients
C
g
: 7
Representative C
1
: 35
Pressure Connections
1/4 in. NPT female
Approximate Weight
68 Series: 0.5 lb (0.23 kg)
168 Series: 3 lb (1.35 kg)
168H Series: 5 lb (2.25 kg)
1. This term is defined in ISA Standard S51.1-1979.
Table 2. Maximum Pressures and Spring Part Numbers
COMPLETE
SWITCHING
VALVE
DIAPHRAGM PRESSURE
CHANGE BETWEEN
SWITCHING POINTS
DIAPHRAGM
PRESSURE RANGE
KEY 8, FIGURE 3
DIAPHRAGM
SPRING PART
MAXIMUM
ALLOWABLE
BODY
KEY 2D, FIGURE 4
BODY SPRING PART
NUMBER AND
BODY
ASSEM-
BLY TYPE
VALVE
TYPE
Minimum
Maximum
PRESSURE RANGE
SPRING PART
NUMBER AND
BODY
PRESSURE
NUMBER AND
COLOR CODE
BLY TYPE
NUMBER
TYPE
NUMBER
Psi
Bar
Psi
Bar
Psi
Bar
NUMBER AND
COLOR CODE
Psi
Bar
COLOR CODE
NUMBER
– – –
– – –
– – –
– – –
– – –
– – –
– – –
– – –
150
10.3
1U878037022, metallic
68-2
168-1
168-2
168-3
168-4
10
10
10
7
0.7
0.7
0.7
0.5
58
38
58
38
4.0
2.6
4.0
2.6
2 to 60
2 to 40
2 to 60
2 to 40
0.1 to 4.1
0.1 to 2.8
0.1 to 4.1
0.1 to 2.8
1U877127142, green
1U879727142, yellow
1U877127142, green
1U879727142, yellow
150
150
40
40
10.3
10.3
2.8
2.8
1U878037022, metallic
1U878037022, metallic
1U854537022, yellow
1U854537022, yellow
68-1
68-1
68-3
68-3
168H-1
168H-2
168H-3
168H-4
20
20
20
16
1.4
1.4
1.4
1.1
100
65
100
65
6.9
4.5
6.9
4.5
50 to 150
35 to 100
50 to 150
35 to 100
3.5 to 10.3
2.4 to 6.9
3.5 to 10.3
2.4 to 6.9
1U877127142, green
1U879727142, yellow
1U877127142, green
1U879724142, yellow
150
150
40
40
10.3
10.3
2.8
2.8
1U878037022, metallic
1U878037022, metallic
1U854537022, yellow
1U854537022, yellow
68-1
68-1
68-3
68-3
The 68 Series body assemblies can be installed in any
position. Position a 168 or 168H Series switching
valve so that moisture and other foreign material can-
not enter either the vent (key 17, figure 3) or the small
hole in the end of the stem protector (key 10, figure 3).
When the switch is in service, inspect the vent open-
ing periodically to ensure that it is not plugged.
Before installing, be certain that the valve body portion
and adjacent pipes are free of pipe scale and other
foreign material. Use accepted piping practices when
installing.
For the 168 and 168H Series switching valves, a
mounting bracket (key 15, figure 3) is available. This
mounting bracket is suitable for use with a 2-inch
(nominal) pipestand. Mounting parts that can be used
to attach a 168 or 168H Series switching valve to the
yoke of a control valve actuator are also available.
Pipe the common pressure line to port A (the connec-
tion in the end of the valve body portion). With one
port (either B or C) plugged, the unit can be used as
an on/off switch. Note that flow cannot pass from port
B to port C or from port C to port B.
168 and 168H Series Adjustment
Determine the desired upper and lower switching pres-
sures (the high and low values of diaphragm pressure
at which the valve is to switch). Refer to table 2 to en-
sure that these pressures are within the diaphragm
pressure range and that the diaphragm pressure
change between the switching pressures is within the
minimum and maximum limits shown.
Adjust the unit as follows. Key numbers used in this
procedure are shown in figure 3 except where indi-
cated.
1. Remove screws and stem protector (keys 11 and
10).
2. To set the lower switching pressure:
2.1 Apply a pressure to the diaphragm case (key
1) equal to the lower switching point.