• Easy Maintenance—Simple design of the controller allows fast, easy maintenance and minimal spare parts inventory.
• Easy Adjustment—Adjustments of set point and zero and span of the process pointer, and switching between direct and reverse action are accomplished quickly and without special tools. Also, the set point and proportional band can be adjusted with no interaction between the two adjustments.
• Highly Visible Display—Two red pointers on a 114 mm (4.50 inch) long white-on-black scale show differential pressure and deviation from set point at a glance. Two other gauges monitor supply and output pressures.
• Low Air Consumption—Relay and nozzle design reduces steady state air consumption to as low as 0.13 normal m3/hr (5 scfh).
• Corrosion Resistant—Thermoplastic housing withstands a broad range of corrosive environments. Internal constructions are available to resist a corrosive supply pressure media.

Available Configurations

See table 1

Sensing Element Range (Input Signal)

See table 2

Process Scale

■ Linear, ■ square root, or ■ others(1) on request

Process Connections

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

Output Signal

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

Supply and Output Connections

1/4 NPT internal

Supply Pressure Requirements(2)

See table 3

Supply Pressure Medium

Air or natural gas(3)

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 4

Controller Adjustments

Proportional Band: 5 to 500% of process scale range
Reset: Adjustable from 0.01 to more than 74 min per repeat (from 100 to less than 0.0135 repeats per min)
Differential Gap Controllers: Adjustable from 1 to 100% of process scale range
Set Point: Continuously adjustable from 0 to 100% of the scale range.

Controller Performance(4)

Repeatability: 0.4% of process scale range
Dead Band: Less than 0.2% of process scale range

Steady-State Air Consumption(5,6)

0.2 to 1.0 bar (3 to 15 psig) Output: 0.13 normal m3/hr (5.0 scfh)
0.4 to 2.0 bar (6 to 30 psig) Output: 0.19 normal m3/hr (7.0 scfh)

Delivery Capacity(5)

0.2 to 1.0 bar (3 to 15 psig) Output: 5.6 normal m3/hr (210 scfh)
0.4 to 2.0 bar (6 to 30 psig ) Output: 9.9 normal m3/hr (370 scfh)

Exhaust Capacity(5)

0.2 to 1.0 bar (3 to 15 psig) Output: 4.6 normal m3/hr (170 scfh)
0.4 to 2.0 bar (6 to 30 psig ) Output: 7.0 normal m3/hr (260 scfh)

Operative Ambient Temperature Limits(2,7)

-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 is mounted on a pipestand

Approximate Weight

Controller: 4.5 kg (10 lb) without the differential pressure unit
Differential Pressure Unit: 21.5 kg (47 lb)
Total Weight (controller and differential pressure unit): 26 kg (57 lb) (with a Barton 199 Differential Pressure Unit)

4194H Series Controllers

Refer to the proportional-only control diagram in figure 2. The input element is connected to the process pointer and flapper by a connecting linkage.
As the process differential 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 counters the flapper movement that resulted from the process differential pressure change, and backs the flapper away from the nozzle. Set point adjustment also changes the proximity of the nozzle and flapper; however, when the set point is changed, the nozzle moves with respect to the flapper. When the controller is in the reverse-acting mode (see flapper detail in figure 2), an increase in process differential pressure causes a decrease in output pressure.
In addition to the Type 4194HA (proportional-only) version, the Type 4194HB controller is available for proportional-plus-reset control. In this controller, output pressure is fed back to the reset bellows as well as to the proportional bellows. Remote set point is available on all controllers. Anti-reset windup is available on all controllers with reset.
The Type 4194HS controller provides differential gap control. In this version, feedback pressure is piped directly to the reset bellows, reinforcing the change in flapper position rather than the counteracting it.
This construction causes the controller output to switch from full supply pressure to zero pressure or vice versa.
The schematic diagram (figure 2) emphasizes detail of construction variations between control modes. Refer to table 1 for a complete description of type number suffixes.

Auto/Manual Option

Controllers with the auto/manual option have piping on the output side of the relay as shown in figure 3. 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 MAN position, the output of the manual loader, which is adjustable by the manual loader knob, is channelled through the auto/manual switch and becomes the output of the controller. When the auto/manual switch is in the AUTO position, the output of the relay is channelled through the switch to become the output of the controller.
Before the auto/manual switch is operated, the output of the relay must equal the output of the manual loader 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. When the pressures are equal, the metal ball is centered in the tube. Pressure imbalance will force the ball to one end of the tube where it forms a seal, blocking air flow through the tube.

Simple 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 prevent excessive pressure buildup inside the case, thus preventing structural damage.

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 5).

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 differential gap control requires the addition of one piece of tubing.

Anti-Reset Windup

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

Remote Set Point

The capability of adjusting the set point from a remote location is available as an option on the 4194H Series controllers.

Auto/Manual Capability

An internal auto/manual station is available for smooth bumpless transfer from automatic to manual and manual to automatic control of the controller output. The two-position switch, showing either automatic or manual mode, is clearly visible with the controller cover closed.

External Feedback

In controller override applications, this option minimizes reset windup in the secondary controller (see figure 4). This option is available only with the two-mode (4194HB Series) controllers.

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 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 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 purchase and end-user.