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, and maintenance of any product remains with the purchaser and end-user.

Available Configurations

See table 1

Process Sensor Range (Input Signal)

Lower and Upper Range Limits: As shown in tables 2 and 5.
Maximum Allowable Pressure: As shown in tables 2 and 5.

Process Scale

Standard scale is matched to the range of the sensing element, with exception of receiver controllers. Optional scales available(1).

Process Connections

Standard: 1/4 NPT internal stainless steel (all input ranges)
Optional: 1/2 NPT external adaptors (see table 3)

Output Signal

Proportional, Proportional-Plus-Reset, or Proportional-Plus-Reset-Plus-Rate Range: ■0.2 to 1.0 bar (3 to 15 psig) or ■0.4 to 2.0 bar (6 to 30 psig)
Differential Gap Range: ■0 to 1.4 bar (0 to 20 psig) or ■0 to 2.4 bar (0 to 35 psig)
Action: Field-reversible between ■direct (increasing sensed pressure increases output pressure), and ■reverse (increasing sensed pressure decreases output pressure) action

Supply and Output Connections

1/4 NPT internal

Supply Pressure Requirements(2)

See table 4

Remote Set Point Pressures

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

Construction Materials

See table 6

Controller Adjustments

Proportional Band: 5 to 500% of process scale span
Reset: Adjustable from 0.01 to more than 74 minutes per repeat (from 100 to less than 0.0135 repeats per minute)
Rate: Adjustable from 0 to 20 minutes
Differential Gap Controllers: Adjustable from 5 to 100% of process scale span
Set Point: Adjustable from 0 to 100% of the scale span

Controller Performance

Repeatability: 0.4% of output span
Dead Band: Less than 0.4% of process scale span
Typical Frequency Response: 1.5 hertz and 90 degree phase shift with 3.05 m (10 feet) of 6.4 mm (1/4-inch) tubing and 1639 cm3 (100 cubic inch) volume

Steady-State Air Consumption(3,4)

0.2 to 1.0 Bar (3 to 15 Psig) Output: 0.10 normal m3/hr (3.5 scfh)
0.4 to 2.1 Bar (6 to 30 Psig) Output: 0.14 normal m3/hr (5.0 scfh)

Delivery Capacity(3)

0.2 to 1.0 Bar (3 to 15 Psig) Output: 5.9 normal m3/hr (240 scfh)
0.4 to 2.1 Bar (6 to 30 Psig) Output: 10.4 normal m3/hr (350 scfh)

Exhaust Capacity(3)

0.2 to 1.0 Bar (3 to 15 Psig) Output: 4.6 normal m3/hr (186 scfh)
0.4 to 2.1 Bar (6 to 30 Psig) Output: 7.0 normal m3/hr (295 scfh)

Operative Ambient Temperature Limits(2,5)

-40 to 70°C (-40 to 160°F)

Hazardous Area Classification

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

Housing

Designed to NEMA 3 (Weatherproof) and IEC 529 IP54 Specifications

Mounting

Controller can be mounted on ■actuator, ■panel, ■wall, or ■pipestand

Approximate Weight

4.5 kg (10 pounds)

• Easy Maintenance—Simple design allows fast, easy maintenance and minimal spare parts inventory.
• Easy Adjustment—Adjusting the set point, the zero and span of the process pointer, and switching between direct and reverse action are accomplished quickly and without special tools. Additionally, the set point and proportional band can be adjusted with no interaction between the two adjustments.
• Application Versatility—Either a Bourdon tube or capsular input element is available to control a wide range of positive pressures, vacuum pressures, or compound pressures.
• Mounting Versatility—A 4195K Series controller can be mounted directly on the actuator (figure 1) or it can mount on a pipestand, wall, or in a panel.
• Vibration Resistance—The simple design and low mass of internal parts allow a 4195K Series controller to withstand the vibration levels encountered in most plant environments.
• High-Visibility Display—Two red pointers on a 114 mm (4 1/2-inch) long, white-on-black scale show process pressure and deviation from set point at a glance. Two other gauges monitor supply pressure and output pressure.
• Low Air Consumption—The relay and nozzle design reduces steady-state air consumption to as low as 0.094 m3/hr (3.5 scfh).
• Corrosion Resistance—Tough, plastic housing resists such corrosive environments as chemical plants and the salt spray atmosphere on an offshore oil platform. Internal constructions are available to resist a corrosive supply pressure media.

Simplified Relay Maintenance

A clean-out wire provides a fast, easy means of cleaning the relay primary orifice during service.

Pressure Protection For The Case

A rubber plug in the plastic case pops out to relieve excessive pressure buildup inside the case.

Easy Direct/Reverse Switching

Controller action can be switched from direct to reverse or vice versa by simply loosening the screws on the proportional band cover and moving the cover out to rotate the proportional band knob to the desired action (see figure 2).

Easy Mode Conversion

Conversion from proportional to proportional-plus-reset control requires the addition of a reset valve and two pieces of tubing. Conversion from proportional to proportional-plus-reset-plus-rate control requires the addition of a reset/rate valve and three pieces of tubing. Conversion from proportional to differential gap for on/off control requires the addition of one piece of tubing.

Anti-Reset Windup

Anti-reset windup is available with proportional-plus-reset controllers. A relief valve may be installed to limit reset windup in either direction.

Remote Set Point

The capability to adjust the set point from a remote location is available as an option on the 4195K Series controllers.

Auto/Manual Capability

An optional internal auto/manual station permits smooth, bumpless transfer between automatic control and manual operation without disturbing the controller output. A positive-acting, two-position switch, showing either automatic or manual control mode, is clearly visible with the controller cover closed.

Proportional-Only Controllers (4195KA Series)

The input element is connected to the process pointer and to the flapper by connecting links. As the process pressure increases (in a direct-acting controller), the flapper moves toward the nozzle, restricting flow through the nozzle and increasing nozzle pressure. When this occurs, relay action increases the output pressure (delivery) of the controller. Output pressure is fed back to the proportional bellows. The action of the proportional bellows counteracts the flapper movement that resulted from the process pressure change and backs the flapper away from the nozzle until equilibrium is reached.
The set point adjustment changes the proximity of the nozzle and flapper as does a change in process pressure except that when the set point is changed, the nozzle moves with respect to the flapper.
The proportional band adjustment knob positions the nozzle on the flapper. Increasing (widening) the proportional band moves the nozzle to a position on the flapper where less input and more feedback motion occurs, which decreases the gain of the controller.
Decreasing (narrowing) the proportional band moves the nozzle toward a position where more input and less feedback motion occurs, which increases the gain. The controller action is changed from direct to reverse by turning the proportional band adjustment knob to position the nozzle on the flapper quadrant to a point where the direction of the flapper motion versus input motion is reversed (see flapper detail in figure 3). With the controller in the reverse-acting mode, an increase in process pressure causes a decrease in output pressure.

Proportional-Plus-Reset and Proportional-Plus- Reset-Plus-Rate Controllers (4195KB and KC Series)

The operation of proportional-plus-reset controllers (4195KB Series) is similar to that of proportional-only controllers (described above). However, in 4195KB Series controllers, output pressure is fed back to the reset bellows as well as to the proportional bellows. In operation, proportional-plus-reset controllers minimize the offset between the process pressure and set point.
As the process pressure increases (in a direct-acting controller), the flapper moves toward the nozzle, restricting flow through the nozzle and increasing nozzle pressure. When this occurs, relay action increases the output pressure (delivery) of the controller. Output pressure is fed back to the proportional bellows and to the reset bellows.
The action of the proportional bellows quickly counteracts the flapper movement that resulted from the process pressure change and backs the flapper away from the nozzle. Pressure in the reset bellows opposes the action of the proportional bellows and slowly moves the flapper closer to the nozzle. Thus, when the process pressure changes, proportional action temporarily reduces the gain of the controller for improved stability. The process pressure then slowly returns to set point, as pressure in both bellows equalizes via the reset action.
The set point adjustment changes the proximity of the nozzle and flapper as does a change in process pressure. However, when the set point changes, the nozzle moves with respect to the flapper.
The proportional band adjustment knob positions the nozzle on the flapper. Increasing (widening) the proportional band moves the nozzle to a position on the flapper where less input and more feedback motion occurs, which decreases the gain of the controller. Decreasing (narrowing) the proportional band moves the nozzle toward a position where more input and less feedback motion occurs, which increases the gain.
The controller action is changed from direct to reverse by turning the proportional band adjustment knob to position the nozzle on the flapper quadrant to a point where the direction of the flapper motion versus input motion is reversed. With the controller in the reverse-acting mode, an increase in process pressure causes a decrease in output pressure.
A 4195KC Series controller also has a rate valve, which is an adjustable restriction that momentarily increases the controller gain to accelerate the corrective action for slow pressure systems. A proportional-plus-reset-plus-rate controller responds to a change in process pressure as follows: First, the rate action delays the proportional action just long enough to allow the controller to respond to the change quickly with high gain, but not long enough for the high gain to cause instability. Then, the low gain provided by the proportional action keeps the system stable. Finally, reset action slowly increases the gain and returns the process pressure toward the set point.

Differential Gap (For On-Off Control) Controllers (4195KS Series)

The operation of differential gap controllers (4195KS Series) is similar to that of proportional-only controllers (described above). However, in 4195KS Series controllers, as the process pressure increases, approaching the upper switching point, the flapper moves toward the nozzle (in a direct-acting controller). This movement restricts the flow through the nozzle and increases nozzle pressure. When this occurs, relay action increases the output pressure (delivery) of the controller. Output pressure is fed back to the positive feedback bellows. The action of the positive feedback bellows moves the flapper closer to the nozzle, increasing nozzle pressure, which in turn, increases the relay output. Output pressure to the final control element switches to full supply pressure.
As the process pressure decreases, approaching the lower switching point, the flapper moves away from the nozzle (in a direct-acting controller) reducing nozzle pressure. Through relay action, pressure to the positive feedback bellows is reduced, moving the flapper farther away from the nozzle, and further reducing nozzle pressure. Output pressure to the final control element switches to zero.
The set point adjustment changes the proximity of the nozzle and flapper as does a change in process pressure except that, when the set point is changed, the nozzle moves with respect to the flapper. The set point adjustment moves both the upper and lower switching points.
The proportional band knob positions the nozzle on the flapper. Increasing (widening) the proportional band moves the nozzle away from the input connection. When the proportional band adjustment moves the nozzle across the feedback connection, the controller action changes between direct and reverse. On a direct-acting controller, changing the proportional band adjustment will widen or narrow the differential gap between the two switching points. This is accomplished by moving the position of the lower switching point. On a reverse-acting controller, changing the proportional band adjustment will widen or narrow the differential gap between the two switching points by moving the position of the upper switching point.

Remote Set Point Option (Suffix Letter M)

The capability to adjust the controller set point from a remote location is available for all 4195KA Series controllers. With this option, a control pressure is applied to the capsular element within the remote set point assembly. The expansion and contraction of the capsule moves the set point adjustment via connecting linkage. Increasing the control pressure to the capsule increases the set point setting, and decreasing the control pressure reduces the set point setting. This option is designated by the letter M in the type number.

Auto/Manual Station Option (Suffix Letter E)

A controller with the auto/manual option (designated by the letter E in the type number) has piping on the output side of the relay as shown in figure 4. Supply pressure to the relay is also applied to the manual loader. The manual loader, functioning as a regulator, applies pressure to one side of the plastic tube and to the auto/manual switch. Output pressure from the relay registers on the other side of the plastic tube as well as in the auto/manual switch.
When the auto/manual switch is in the MANUAL position, the manual loader output is channeled through the auto/manual switch and becomes the controller output. When the auto/manual switch is in the AUTO position, the relay output is channeled through the switch to become the controller output.
Before the auto/manual switch is operated, the relay output must equal the manual loader output to avoid bumping the process. Adjusting the set point varies the pressure on the left-hand side of the plastic tube. Adjusting the manual loader knob varies the pressure on the right-hand side of the plastic tube. When the pressures are equal, the metal ball is centered in the tube and is held in place by a small magnet. Pressure imbalance forces the ball to one end of the tube where it forms a seal, blocking air flow through the tube.

Anti-Reset Windup Option (Suffix Letter F)

Anti-reset windup is available for all 4195KB and KC Series controllers and is designated by the letter F in the type number. The differential relief valve operates when the difference between the proportional bellows pressure and the reset bellows pressure reaches a predetermined value. Anti-reset windup reduces overshoot of the process pressure that can result from a large or prolonged deviation from set point.

External Feedback Option

External feedback is available for all 4195KB Series controllers. Controllers with this option have an external connection on the bottom of the controller case (see figure 7). This connection breaks the positive feedback (reset) loop inside the controller and brings it outside (see figure 5).
The connection allows the positive feedback loops of two controllers (primary and secondary) to be tied together when the controllers are used in an override application. When connected, the secondary controller reset pressure tracks the primary controller output pressure, minimizing reset windup in the secondary controller.

• Application

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

• Construction

Refer to the specifications and to the Construction Features section. Carefully review each specification and feature, indicating your choice whenever a selection is to be made. Refer to table 1 for type numbers; add an R to any type number if reverse action is desired.

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, and maintenance of any product remains with the purchaser and end-user.