• Easy Maintenance—Simple design of the receiver-controller allows fast, easy maintenance and minimal spare parts inventory.
• Easy Adjustment—Proportional band and reset adjustment is accomplished quickly and without special tools. The control set point is manually adjustable in the case or through remote air loading (figures 4 and 5).
• Application Versatility—Reset may be added to a receiver-controller originally furnished without it.
• Mounting Versatility—2506 and 2516 receiver-controllers may be attached to the casing or yoke of a control valve actuator, or placed anywhere between the transmitter and valve.
• Stable Control—A pressure balanced relay provides intermittent bleed and gives accurate, stable control. The addition of reset action on the 2516 unit offers drift compensation, yet provides smooth, stable control.
• Easy Reversibility—2506 and 2516 receiver-controllers may be changed from direct to reverse action, or vice-versa, by simply repositioning the reversing switch.

Available Configurations

For additional information, refer to table 2 2506: A receiver-controller that is set for either proportional or snap action (S) control or is set for either direct or reverse (R) action
2516: A 2506 that also provides proportional-plus-reset control
2516F: A 2516 that also provides anti-reset windup control

Input Signal

■0.2 to 1.0 bar (3 to 15 psig) or ■0.4 to 2.0 bar (6 to 30 psig)

Output Signal(1)

See table 1

Output Action

Direct Action: An increasing fluid, interface level, or density increases output pressure or,
Reverse Action: An increasing fluid, interface level, or density decreases output pressure

Remote Set Point Signal

From a control device, provide a remote set point signal that is 0.2 to 1.0 bar (3 to 15 psig) or 0.4 to 2.0 bar (6 to 30 psig) that matches the receiver-controller input signal range

Supply Pressure(2)

Normal Operating Pressure: See table 1..
Maximum Pressure to Prevent Internal Part Rupture(1): 3.4 bar (50 psig)

Steady State Air Consumption

See figure 3

Proportional Band, Reset, and Anti-Reset Windup

See table 2

Performance

Hysteresis: 0.6 percent of output pressure change at 100 percent of proportional band, or differential gap

Standard Supply and Output Pressure Gauge Indications

See table 1

Standard Tubing Connections

1/4 NPT internal

Operative Ambient Temperature Limits(2)

Standard: -40 and 71°C (-40 and 160°F)
High Temperature: -18 and 104°C (0 and 220°F)

Hazardous Area Classification

2506 Series receiver-controllers comply with the requirements of ATEX Group II Category 2 Gas and Dust

Construction Materials

Case and Cover: Die-cast aluminum
Flapper: K93600 nickel alloy
Bellows: ■Bronze (standard) or ■stainless steel (optional)
Nozzle: C36000 (Brass)
Proportional Band Valve Body, Seat, and Plug: Brass
Gaskets: ■Chloroprene (standard) or ■silicone (high temperature)
Relay Body: Aluminum/brass
Relay Valve Plug and Seats: Brass
Relay Diaphragm: ■Nitrile (standard) or
■polyacrylate (high temperature)
Reset Valve Body, if Used: Die-case zinc
Reset Valve Plug and Seat Ring, if Used:
18-8 stainless steel

Approximate Weight

4.53 kg (10 pounds)

Dimensions

Refer to figure 7

Options

■Reverse action; ■Instrument pressure gauge; ■stainless steel bellows; Gauge markings in ■bar, ■kg/cm2, ■kPa, or ■Psig/kPa; and ■High temperature gasket and relay materials

2506 Receiver-Controller

The principle of operation for the direct acting 2506 receiver-controller is illustrated in figure 4.
Supply pressure enters the inlet side of the relay and input pressure from the transmitter enters the reversing switch. Output pressure from the receiver-controller is delivered to the diaphragm of the control valve actuator.
As long as the transmitter input pressure and process level remain constant, the bellows beam remains motionless. This allows the supply pressure to bleed through the nozzle as fast as it enters the relay through the fixed restriction.
If there is an increase in pressure from the transmitter, pressure increases in the sensing bellows assembly, tending to push the beam toward the nozzle. This action builds up pressure in the relay's upper chamber as air continues to pass through the fixed restriction. The buildup of pressure in the upper chamber pushes the relay diaphragm assembly downward, opening the relay supply valve. Supply pressure then flows into the relay's lower chamber until the relay diaphragm assembly is pushed back to its original position and the relay valve is closed again. The increased pressure in the lower chamber is transmitted to the diaphragm of the control valve actuator.
At this same time, pressure in the proportional bellows assembly is being increased through the 3-way proportional valve assembly, which causes the beam to move away from the nozzle, thus stopping the pressure buildup in the relay's upper chamber. The receiver-controller is again in equilibrium with an increased input from the transmitter and an increased output to the diaphragm of the control valve actuator. If a decrease in transmitter input pressure occurs, the reverse of the above cycle takes place, with a decrease in output pressure.

2516 Receiver-Controller

The principle of operation for the 2516 receiver-controller is the same as the 2506 receiver-controller, but includes a reset adjustment. Refer to figure 5.
Note from the principle of operation of the 2506 receiver-controller that an increase in pressure from the transmitter increases the pressure in the sensing bellows, moves the beam toward the nozzle, increases the pressure to the control valve, and at the same time increases the pressure through the proportional valve to the proportional bellows, thus stopping the pressure buildup to the control valve.
With the 2516 receiver-controller, the pressure in the line leading to the proportional bellows slowly passes through the reset valve and builds up the pressure in the reset bellows. Pressure buildup in the reset bellows pushes the beam toward the
nozzle, again increasing the pressure throughout the system to the control valve actuator and proportional bellows. Increased pressure to the control valve actuator increases pressure through the reset valve to the reset bellows and starts another increase in the pressure throughout the system and to the control valve. This pressure buildup in the system continues until the pressure from the transmitter is decreased and the system is brought back to the set point.
If a change in the system causes a decrease in outlet pressure, the reverse of the above cycle takes place.
The above pressure changes are simultaneous and are described above as a step-by-step sequence for explanation purposes only.
The reset adjustment dial on the 2516 receiver-controller is calibrated in minutes per repeat. This is the time in minutes required for the reset action to produce a quantity correction which is equal to the correction produced by proportional control action. In other words, this is the time in minutes required for the controller to increase its output pressure by an amount equal to previous proportional increase caused by a change in control conditions.

2516F Receiver-Controller

During a prolonged difference between set point and the controlled variable, such as encountered with intermittent control applications (e.g., batch temperature control or wide open monitors on pressure control), reset ramps the controller output to either zero or full supply pressure; this condition is reset windup. When the controlled variable crosses the set point, there will be a delay before the
controller output responds to the change in controlled variable. Anti-reset windup minimizes this delay and permits returning the controlled variable to set point more quickly with minimal overshoot.
The 2516 receiver-controller also has an anti-reset windup relief valve (2516F). Refer to figure 5. This valve provides differential pressure relief to prevent proportional pressure from exceeding reset pressure by more than a set value. The valve consists of two pressure chambers separated by a spring-loaded diaphragm. Reset pressure registers on the spring side of the diaphragm and proportional pressure registers on the other side. As long as controlled pressure changes are slow enough for normal proportional and reset action, the relief valve spring will keep the relief valve diaphragm from opening. However, a large or rapid increase in controller pressure will cause the relay to increase loading pressure to the control device. The increase in controller pressure also causes the pressure to increase in the proportional system and on the proportional side of the relief valve diaphragm. If this increase is greater than the relief valve spring setting, the relief diaphragm moves off the orifice in the differential relief valve. This allows the pressure on the proportional side of the diaphragm to bleed into the reset system. This action provides quick relief of excessive proportional pressure and reduces the time required by the system to return to the control point. A user can reverse the differential relief action to relieve on decreasing output pressure.

Application

1. Description of the service, such as throttling or on-off
2. Pressure range, composition, and temperature of the process fluid
3. Ambient temperature

Construction

Refer to the specifications. Carefully review each specification, indicating your choice whenever a selection is to be made.

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