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Type 4660 High-Low Pressure Pilot

4660 Pressure Pilot Description The Type 4660 pneumatic high-low pressure pilot (figure 1) activates safety shutdown systems for flowlines, production vessels, and compressors. This pilot is available with either single or dual set point capability, using patented switch points, to maintain full output pressure when the process pressure is within the set point range. If the process pressure is outside this range, the pilot switches from full output pressure to zero output pressure.
The primary switching mechanism in this pilot is a block-and-bleed relay assembly. This construction can be used in both block-and-bleed and bleed-only systems.
Unless otherwise noted, all NACE references are to NACE MR0175-2002.
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Features

  • Superior Performance—Repeatability meets the U.S. Minerals Management Service test tolerances referenced in Outer Continental Shelf (OCS) Order No. 5 and defined in the American Petroleum Institute (API) RP14C standard.
  • Easy Maintenance—Simple modular construction plus a line of prepackaged parts kits makes pilot maintenance fast and easy.
  • Reliable Operation—The pilot uses a field-proven Bourdon tube process pressure sensing element that reduces maintenance by eliminating the need for wetted dynamic O-rings.
  • Environmental Packaging—Construction materials have been selected to protect the pilot from corrosive environments such as the salt spray atmosphere of offshore platforms.
  • Vibration Resistance—The rugged Bourdon tube sensing element and shock-absorbing switch points dampen the effects of vibration while maintaining performance.

  • Set Point Accuracy—Standard high-resolution set point adjustments are easy to set, non-interactive, and can be locked in place to maintain the desired set point. The optional set point indication assemblies on the front panel are easy to read and let you simply dial in the desired set point.
  • Cost-Effective Design—One pilot provides either a high-low function or a single switch point, whichever the application requires.
  • Installation Versatility—Panel, rack, pipestand, or actuator mounting is available to meet field requirements.
  • Operational Indications—A supply pressure test function is provided. The optional output indicator lets you check at a glance whether the pilot output pressure is at full output or zero output pressure.
  • NACE Conformance—An N05500 nickel alloy Bourdon tube is available for those applications where the pilot must meet the requirements of NACE Standard MR0175-2002.

Note
Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use, or maintenance of any product. Responsibility for the selection, use, and maintenance of any product remains with the purchaser and end-user.

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Specifications

Available Configurations

■High-low, ■low-only, or ■high-only set point capability

Input Signal

Type: Process pressure sensed with a Bourdon tube
Bourdon Tube Ratings: See table 1 or 2 Overpressure Protection: Maximum allowable emergency process pressures and maximum allowable process pressures to ensure set point readjustability are shown in table 3

Output Signal

■Zero pressure or ■full supply pressure (automatically resets)

Supply Pressure(1)

Normal Operating Pressure: 1.4 to 4.4 bar (20 to 65 psig)
Medium: Air or natural gas(2) Quality: Should be dry with solid particles removed

Steady-State Air Consumption(3)

Output Signal at 0 psig: ≤0.134 normal m3/hr (≤5 Scfh)
Output Signal at Full Supply Pressure: ≤0.00134 normal m3/hr (≤0.05 Scfh)

Set Point Adjustments

Continuously adjustable between 3 and 97% of Bourdon tube rating; see table 1 or 2 for ranges

Performance in Percentage of Bourdon Tube Rating

Repeatability: ≤0.25%
Set Point ΔPmin .
(See table 1 or 2)
Single High-Low Unit: 10% for up to 170 bar (2500 psig) Bourdon tubes; 15% for 350, 500, and 700 (NACE) bar (5000, 7500, and 10,000 (NACE) psig) Bourdon tubes
Low-Only and High-Only Pair: 3%
Trip-to-Reset Zone: ≤1.5% (see table 1 or 2)

Exhaust Capacity

Cg ≥15

Construction Materials

Case and Cover: Polyester
Front Cover: Tinted polycarbonate with scratch-resistant coating
Base: Hard-anodized nickel-sealed aluminum alloy
Bourdon Tube: ■316 stainless steel, or ■N05500 nickel alloy
Relay Body, Relay Flange, Nozzle/Flapper Assembly Orifice Block, and Switch Point. Housings: Glass-filled polyphenylene sulfide
Relay Diaphragm: ■Nitrile/Polyester or ■Fluorosilicone/Polyester (low temperature version), or ■Fluorocarbon/Polyester
Relay Disks: ■Nitrile, ■Fluorosilicone (low temperature version), or ■Fluorocarbon/Polyester
Process Pressure Block, Tubing, Front Plate, Flapper, Linkages, and Other Major Metal Parts: Stainless steel
Gaskets: Chloroprene and nitrile
O-Rings.
Relay: ■Nitrile or ■Fluorocarbon
Switchpoint Assembly: Nitrile impregnated with molybdenum disulphide
Base/Case: Nitrile

Operating Conditions(1)


Condition Normal Operating Limits Nominal Reference
Ambient Temperature Nitrile Elastomers:
-40 to 60°C
(-40 to 140°F)
21°C (70°F)
Fluorocarbon Elastomers:
-7 to 71°C
(-20 to 160°F
Fluorosilicone Elastomers: (Low Temperature Version)
-75°F (-59°C)
Process Temperature -29 to 93°C
(-20 to 200°F)
21°C (70°F)

Operating Influences on Switch Point Sensitivity

Supply Pressure: ≤0.05% of Bourdon tube rating for a 10% change in supply pressure
Ambient Temperature: ■≤1.5% (standard construction) or ■≤2.5% (low temperature version) of Bourdon 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 the Bourdon tube rating

Pressure Connections

1/4 NPT internal

Mounting

■Panel, ■rack, ■pipestand, or ■actuator

Hazardous Area Classification

Complies with the requirements of ATEX Group II Category 2 Gas and Dust

Approximate Weight

2.3 kg (5 pounds)

Options

■Visual output indication, ■fluorocarbon elastomers in relay, ■low-temperature version to -59°C (-75°F) ■316 stainless steel panel mounting flange, ■set point indication, and ■tamper-resistant front cover


NOTE: Specialized instrument terms are defined in ANSI/ISA Standard 51.1 - Process Instrument Terminology.
1. The pressure/temperature limits in this document and any applicable standard or code limitation for valve should not be exceeded.
2. Natural gas to contain no more than 20 ppm of H2S.
3. Normal m3/h--Normal cubic meters per hour at 0°C and 1.01325 bar, absolute. Scfh--Standard cubic feet per hour at 60°F and 14.7 psia.
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Principle of Operation Refer to figure 2.
Process pressure is connected to the Bourdon tube sensing element. While the process pressure remains in the adjusted set ranges (between the low set point and the high set point), the flapper does not contact either set point pivot. This keeps the nozzle capped and maintains full output pressure.
As the process pressure decreases below the low set point value, the radius of arc of the Bourdon tube contracts. This causes the flapper to contact the low set point pivot and uncap the nozzle, which blocks supply pressure and vents (bleeds) output pressure. As the process pressure increases above the high set point value, the radius of arc of the Bourdon tube extends. This causes the flapper to contact the high set point pivot, also uncapping the nozzle and providing block-and-bleed action. When the process pressure returns to the set range, the nozzle is again capped, switching the relay back to maintain full output pressure.
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Performance The performance characteristics shown in figure 3 and table 4 illustrate several important functional parameters.
SL represents the low set point and SH represents the high set point. The set range capability is 3 to 97 percent of the Bourdon tube rating. However, with a single high-low unit or a high-only/low-only pair, there is a limit on how close to each other the set points can be adjusted. This limit is defined as set point ΔPMIN and is shown as SL′ and SH′.
Trip-to-reset is the combined effect of pilot deadband and hysteresis. After the pilot has tripped, it automatically resets when the process pressure returns to the set range. However, full output pressure is not instantaneous. The difference between the set point and reset to full output pressure is the trip-to-reset zone. This parameter is also a function of the Bourdon tube rating as shown in figure 3 and table 4.
Repeatability is the switch point deviation around the set point as a percentage of the Bourdon tube rating.
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Applications Figure 4 shows some of the many ways in which the Type 4660 high-low pressure pilot may be connected to accommodate requirements for single and dual outputs as well as single and dual process pressure lines. Examples A and D in figure 4 show how a pair of high-only and low-only pilots are connected to obtain closer set points as specified by the set point ΔPMIN values in tables 1 and 2. Example B or C shows connections for a two-segment flow line configuration that adheres to API Specification RP14C. Example E shows a typical connection to an electrical pressure switch.
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Installation Normal installation is with the pilot mounted vertically and the connections for process pressure, supply pressure, and output pressure facing down. The supply medium should be regulated dry air or natural gas with solid particles removed.
Figures 5 and 6 illustrate the mounting dimensions and the location of the pressure connections.
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Ordering Information When ordering, specify:

Application

  • Bourdon tube rating and material
  • Composition, pressure, and temperature of the process fluid
  • Ambient temperature range
  • Description of application

Construction

Refer to the Specifications table. Review the information under each specification and in the referenced tables; specify the desired selection whenever there is a choice to be made.

Note
Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use, or maintenance of any product. Responsibility for the selection, use, and maintenance of any product remains with the purchaser and end-user.

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Table Table 1. Additional Specifications, Bar
BOURDON TUBE
RATING(1)
SET RANGE(1) SET POINT ΔPMIN (MINIMUM
ALLOWABLE DIFFERENCE
BETWEEN HIGH AND LOW SETTINGS)
TRIP-TO-RESET ZONE
Single High-Low Unit High-Only/
Low-Only Pair
7
17
35
70
0.3 to 6.6
0.6 to 16.6
1.1 to 33.4
2.1 to 67.9
0.7
1.7
3.5
6.9
0.2
0.5
1.0
2.1
≤0.1
0.3
0.5
1.0
100
170
350
500
700(2)
3.2 to 100.2
5.2 to 167.2
10.4 to 334.4
15.6 to 501.5
20.7 to 668.8
10.3
17.2
51.7
70.7
103.4
3.1
5.2
10.3
15.5
20.7
1.6
2.6
5.2
7.8
10.3
1. Rating indicated on Bourdon tube and set range on front panel are in kPa (1 bar = 100 kPa).
2. Available in N05500 nickel alloy only, for NACE.

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Table 2. Additional Specifications, Psig
BOURDON TUBE
RATING
SET RANGE SET POINT ΔPMIN (MINIMUM
ALLOWABLE DIFFERENCE
BETWEEN HIGH AND LOW SETTINGS)
TRIP-TO-RESET ZONE
Single
High-Low Unit
High-Only/
Low-Only Pair
100
250
500
1000
3 to 97
8 to 242
5 to 485
30 to 970
10
25
50
100
3.0
7.5
15
30
≤1.5
3.8
7.5
15
1500
2500
5000
7500
10,000(1)
45 to 1455
75 to 2425
150 to 4850
225 to 7275
300 to 9700
150
250
750
1025
1500
45
75
150
225
300
23
38
75
113
150
1. Available in N05500 nickel alloy only, for NACE

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Table 3. Maximum Allowable Process Pressure(1)
BOURDON TUBE RATING MAXIMUM ALLOWABLE EMERGENCY PROCESS PRESSURE
Bar(2) Psig Stainless Steel Bourdon Tubes N05500 Nickel Alloy Bourdon Tubes (NACE)
Bar(2) Psig Bar(2) Psig
6.9
17.2
34.5
69.0
100
250
500
1000
13.8
34.2
69.0
138.0
200
500
1000
2000
13.8
34.2
69.0
138.0
200
500
1000
2000
103.4
172.4
344.8
517.2
689.5
1500
2500
5000
7500
10,000
206.8
344.8
517.2
646.3
N/A
3000
5000
7500
9375
N/A
206.8
258.6
430.9
568.8
758.5
3000
3750
6250
8250
11,000
Maximum Allowable Process Pressure to Ensure Set Point Readjustability(3)
6.9
17.2
34.5
69.0
100
250
500
1000
13.8
34.8
51.7
103.5
200
500
750
1500
13.8
22.3
53.4
89.7
200
325
775
1300
103.4
172.4
344.8
517.2
689.5
1500
2500
5000
7500
10,000
155.1
172.4
517.2
646.3
N/A
2250
2500
7500
9375
N/A
124.0
227.5
344.8
517.2
689.5
1800
3300
5000
7500
10,000
1. Normal operating process pressures should not exceed the Bourdon tube rating.
2. Ratings indicated on Bourdon tube are in psig and kPa (1 bar = 100 kPa).
3. Values listed for the N05500 nickel alloy Bourdon tubes are for a 2% deviation from set point due to overpressure.

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Table 4. Performance Characteristics
CONSTRUCTION PERCENT OF BOURDON
TUBE RATING
SET POINT
ΔPMIN
TRIP-TO-RESET ZONE REPEATABILITY
Single
High-Low Unit
10(1) 1.5 0.25
High-Only/
Low-Only Pair
3    
1. 5000 and 7500 Psig Bourdon tubes are 15 percent of Bourdon tube rating.

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34.5:4660
March 2008
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