Type 4660
2
Table 1. Specifications
Available Configurations
High-low, low-only, or high-only set point capability
Input Signal
(1)
Type: Process pressure sensed with Bourdon tube
Bourdon Tube Ratings: See table 2 or 3
Overpressure Protection: Maximum allowable
emergency process pressures and maximum allow-
able process pressures to ensure set point readjust-
ability are shown in table 4
Output Signal
(1)
Zero or full supply pressure (automatically resets)
Supply Pressure
(1)
20 to 65 psig (1.4 to 4.4 bar)
Steady-State Air Consumption
(2)(3)
Output Signal at Zero:
≤5 scfh (≤0.134 normal m
3
/hr)
Output Signal at Full Supply Pressure:
≤0.05 scfh (≤0.00134 normal m
3
/hr)
Set Point Adjustments
Continuously adjustable between 3 and 97% of
Bourdon tube rating; see table 2 or 3 for ranges
Performance in Percentage of Bourdon Tube
Rating
Repeatability
(1)
≤0.25%
Set Point DP
min
(see table 2 or 3)
Single High-Low Unit:
10% for up to 2500 psig
(172.4 bar) Bourdon tubes; 15% for 5000 and 7500
psig (344.8 and 517.1 bar) Bourdon tubes
Low-Only and High-Only Pair:
3%
Trip-to-Reset Zone (see table 2 or 3)
≤1.5%
Exhaust Capacity
C
g
≥15
Pilot Supply Flow Requirement
(2)
Pilot requires minimum of 150 scfh
(4.02 normal m
3
/hr) to activate relay
Operating Conditions
(1)
Condition
Normal Operating
Limits
Nominal
Reference
Nitrile Elastomers:
–40 to 140_F
(–40 to 60_C)
Ambient temperature
Fluoroelastomer Elastomers:
20 to 160_F
(–7 to 71_C)
70_F (21_C)
Fluorosilicone Elastomers:
(Low Temperature Version)
–75_F to 160_F
(–59 to 71_C)
Process temperature
–20 to 200_F
(–29 to 93_C)
70_F (21_C)
Operating Influences
(1)
on Switch Point Sensitivity
Supply Pressure: ≤0.05% of Bourdon tube rating
for a 10% change in supply pressure
Ambient Temperature: ≤1.5% (standard construc-
tion) or ≤2% (low temperature construction) of Bour-
don tube rating throughout normal operating limits
with nominal reference
Time: ≤1% of Bourdon tube rating over 30 days at
ambient temperature nominal reference
Process Pressure: Range shift or set point drift
can occur if process pressure exceeds Bourdon
tube rating
Pressure Connections
1/4-inch NPT female
Mounting
Panel, rack, pipestand, or actuator
Approximate Weight
5 pounds (2.3 kg)
Options
J Visual output indication, J flouroelastomers in
relay, J low-temperature version to –75_F (59_C)
J 316 stainless steel panel mounting flange J set
point indication, or J tamper-resistant front cover
1. This term is defined in ISA Standard S51.1-1979.
2. Scfh—standard cubic feet per hour (60_F and 14.7 psia). Normal m
3
/hr—normal cubic meters per hour (0_C and 1.01325 bar absolute).
3. Supply pressure at 35 psig (2.4 bar)
Description
The Type 4660 high-low pressure pilot (figure 1) acti-
vates emergency shutdown systems for flowlines, pro-
duction vessels, and compressors. The pilot can be
used with either a single or dual set point capability to
maintain full output pressure when the process is op-
erating within the set point range. The primary switch-
ing mechanism in this pilot is a block-and-bleed relay
assembly.
Specifications
Specifications for the Type 4660 high-low pressure
pilot are listed in table 1.
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