Product Bulletin
4194 Differential Pressure Controllers
D200048X012
34.4:4194
May 2013
Fisherr 4194 Differential Pressure Indicating
Controllers
Fisher 4194 (low pressure) differential pressure
indicating controllers show process differential
pressure and set point on an easy‐to‐read process
scale. The controllers sense two different pressures
and compare the difference between these pressures
with an operator‐adjusted set point. A pneumatic
signal is then delivered to a control element to change
the process differential pressure toward the set point.
The controllers use a capsular element for differential
pressure up to 2.0 bar (30 psi). They are available for
proportional only, proportional‐plus‐reset, and
differential gap control. The controller is also available
(see table 1) with anti‐reset windup, internal
auto/manual station, and remote set point
adjustability (see table 1). 4194 controllers are used in
industry where process monitoring and accurate
measurement of differential pressures are required.
PROCESS
SET POINT
ADJUSTMENT
PRESSURE
INDICATOR
W5850‐1
CONTROLLER YOKE‐MOUNTED ON
ACTUATOR OF CONTROL VALVE
www.Fisher.com
W5827‐2
SUPPLY
PRESSURE
GAUGE
INTERIOR OF CONTROLLER
OUTPUT
PRESSURE
GAUGE
Product Bulletin
34.4:4194
May 2013
Specifications
4194 Differential Pressure Controllers
D200048X012
Available Configurations
See table 1
Sensing Element Range (Input Signal)
See table 2
Process Scale
J Linear, J square root, or J others on request
(1)
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:
J 0.2 to 1.0 bar (3 to 15 psig) or J 0.4 to 2.0 bar
(6 to 30 psig)
Differential Gap Output:
(0 and 20 psig) or
Action: Field‐reversible between
sensed pressure increases output pressure) or
J 0 and 1.4 bar
J 0 and 2.4 bar (0 and 35 psig)
J direct (increasing
J
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
J 0.2 to 1.0 bar (3 to 15 psig) or J 0.4 to 2.0 bar
(6 to 30 psig)
Differential Gap Controllers: Adjustable from 1 to
100% of process scale range
Set Point: Continuously adjustable from 0 to 100% of
the scale range.
J Internal Set Point Adjustment (standard): Internal
adjustment knob
Controller Performance
(4)
Repeatability: 0.09% of process scale range
Dead Band: Less than 0.2% of process scale range
Typical Frequency Response: 1.5 Hz and 90 deg phase
shift with 3.05 m (10 feet) of 6.44 mm (1/4 inch)
tubing and 1639 cm
Steady‐State Air Consumption
3
(100 in.3) volume
(4)(5)
0.2 to 1.0 Bar (3 to 15 psig) Output:
3
0.09 m
0.4 to 2.0 Bar (6 to 30 psig) Output:
0.13 m
Delivery Capacity
/hr (3.5 scfh)
3
/hr (5.0 scfh)
(4)
0.2 to 1.0 Bar (3 to 15 Psig) Output:
3
/hr (240 scfh)
6.4 m
0.4 to 2.0 Bar (6 to 30 Psig ) Output:
3
9.4 m
/hr (350 scfh)
Exhaust Capacity
0.2 to 1.0 Bar (3 to 15 Psig) Output:
3
5.0 m
/hr (186 scfh)
0.4 to 2.0 Bar (6 to 30 Psig ) Output:
3
7.9 m
/hr (295 scfh)
Operative Ambient Temperature Limits
(4)
(2)(6)
–40 to 70_C (–40 to 160_F)
Hazardous Area Classification
Complies with the requirements of ATEX Group II
Category 2 Gas and Dust
Construction Materials
See table 4
Mounting
Controller can be mounted on
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)
NOTE: Specialized instrument terms are defined in ANSI/ISA Standard 51.1 - Process Instrument Terminology.
1. Consult your Emerson Process Management sales office for additional information.
2. The pressure/temperature limits in this document, and any applicable code or standard should not be exceeded.
3. Natural gas should contain no more than 20 ppm of H
4. Normal m
5. Without auto/manual switch. With auto/manual switch, air consumption is 0.28 normal m
6. Also for transportation and storage limits.
2
3
/hr‐‐normal cubic meters per hour (m3/hr, 0_C and 1.01325 bar, absolute). Scfh‐‐standard cubic feet per hour (ft3/hr, at 60_F and 14.7 psig).
S.
2
3
/hr (10.0 scfh).
J panel, J wall, or J pipestand
Approximate Weight
4.5 kg (10 lb)
J actuator,
4194 Differential Pressure Controllers
D200048X012
Table 1. Available Configurations
TYPE
NUMBER
4194A
4194AE
4194AM
4194AME
4194B
4194BE
4194BF
4194BFE
4194BM
4194BME
4194BFM
4194BFME
4194C
4194CE
4194CF
4194CFE
4194CM
4194CME
4194CFM
4194CFME
4194S
4194SE
4914HSM
4194SME
1. Reverse‐acting constructions are designated by an R added to the type number.
2. Consult your Emerson Process Management sales office for information on rate.
(1)
Proportional‐
Only
X
X
X
X
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
Proportional‐
Plus Reset
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
X
X
X
X
X
X
X
X
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
Proportional‐Plus
Reset‐Plus‐Rate
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
Product Bulletin
34.4:4194
May 2013
CONFIGURATIONS
Differential
(2)
X
X
X
X
X
X
X
X
Gap
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
X
X
X
X
Anti‐Reset
Windup
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
X
X
‐ ‐ ‐
‐ ‐ ‐
X
X
‐ ‐ ‐
‐ ‐ ‐
X
X
‐ ‐ ‐
‐ ‐ ‐
X
X
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
Remote Set
Point
‐ ‐ ‐
‐ ‐ ‐
X
X
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
X
X
X
X
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
‐ ‐ ‐
X
X
X
X
‐ ‐ ‐
‐ ‐ ‐
X
X
Internal Auto/
Manual Station
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
‐ ‐ ‐
X
Features
n Easy Maintenance—Simple design of the controller
allows fast, easy maintenance and minimal spare
parts inventory.
n Easy Adjustment—Adjusting the set point and the
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.
n Vibration Resistant—Simple design and low mass of
internal parts allow the controller to withstand
vibration encountered in most plant environments.
n Low Air Consumption—Relay and nozzle design
reduces steady‐state air consumption to as low as
0.09 m
n Corrosion Resistant—Tough plastic housing resists
3
/hr (3.5 scfh).
corrosive environments. Internal constructions are
available to resist a corrosive supply pressure
media.
n Mounting Versatility—The controller can mount
directly on the actuator or it can mount on a
pipestand, on a wall, or in a panel.
n Highly Visible Display—Two red pointers on a
114 mm (4‐1/2 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.
3
Product Bulletin
34.4:4194
May 2013
Table 2. Process Sensor (Capsular Element) Ranges, and Pressure Ratings
SPAN
(1)
MAXIMUM ALLOWABLE
DIFFERENTIAL PRESSURE
(2)
AVAILABLE CAPSULAR
ELEMENT RANGES
Bar Psid Bar Psid Bar Psid Bar
0 to 0.4 0 to 5 0.2 2.5 0.4 5 -0.4 -10 0.4 5 0.5 7.5
0 to 0.7 0 to 10 0.4 5.0 0.7 10 -0.7 -20 0.7 10 1.0 15.0
0 to 1.4 0 to 20 0.7 10.0 1.4 20 -1.0 -30 1.4 20 2.1 30.0
0 to 2.0 0 to 30 1.0 15.0 2.0 30 -1.0 -30 2.0 30 3.1 45.0
1. Span is adjustable between minimum shown and maximum of the capsular element operating range and can be positioned anywhere within this range. For example, if a (0 to 2.0 bar (0 to 30
psid) capsular element is used and the minimum span of 1.0 bar (15 psid) is set, the process indication can be calibrated to a range of 0 to 1.0 bar (0 to 15 psid), 1.0 to 2.0 bar (15 to 30 psid), or
any value between the minimum and maximum values of the operating range.
2. Maximum difference between the two input supply pressures.
3. Capsular element may be pressured to this valve (after reaching travel stop at upper range limit) without permanent zero shift of structural damage to controller components.
MINIMUM
DIFFERENTIAL
Table 3. Supply Pressure Data
Output Signal Range
Bar
Psig
1. If this pressure is exceeded, control stability may be impaired.
2. If this pressure is exceeded, damage to the controller may result.
0.2 to 1.0 or 0 and 1.4 (differential gap) 1.4 3.4
0.4 to 2.0 or 0 and 2.4 (differential gap) 2.4 3.4
3 to 15 or 0 and 20 (differential gap) 20 50
6 to 30 or 0 and 35 (differential gap) 35 50
Normal Operating Supply
4194 Differential Pressure Controllers
D200048X012
STATIC PRESSURE
OPERATING RANGE
Minimum Maximum
Pressure
Inches of
Mercury
(1)
Bar Psig Bar Psig
MAXIMUM ALLOWABLE
STATIC PRESSURE
Maximum Pressure to Prevent
Internal Damage
(2)
(3)
Table 4. Construction Materials
Part Standard Material Optional Material
Case and cover Polyester plastic ---
Exterior tubing Copper Aluminum, stainless steel, steel, or polyethylene
Exterior fittings C36000 (brass) Aluminum, stainless steel, steel, or polyethylene
Interior tubing S30400 (304 stainless steel) ---
Capsular element N09902 (Nickel alloy) ---
Nozzle S30300 (303 stainless steel) ---
Flapper S31600 (316 stainless steel) ---
Relay springs S30200 (302 stainless steel) or steel ---
Relay O‐rings Nitrile ---
Relay diaphragms Nitrile ---
Other relay metal parts Aluminum or stainless steel ---
Feedback bellows assembly C51000 (bronze) S32100 (321 stainless steel)
Supply and output gauges Brass (wetted parts only) Stainless steel (wetted parts only)
Remote set point bellows N09902 ---
4
4194 Differential Pressure Controllers
D200048X012
Figure 1. Operational Schematic of Fisher 4194 Differential Pressure Controllers
Product Bulletin
34.4:4194
May 2013
MANUAL SET POINT
ADJUSTMENT
PROCESS POINTER
REMOTE SET POINT
CONNECTED HERE
INPUT ELEMENT
CONNECTED HERE
CONNECTING
LINK
SUPPLY PRESSURE
OUTPUT PRESSURE
PROPORTIONAL PRESSURE
NOZZLE PRESSURE
RESET PRESSURE
TO
RESET
BELLOWS
TO
PROPORTIONAL
BELLOWS
BEAM
TO
NOZZLE
PROPORTIONAL
BELLOWS
FLAPPER
NOZZLE
OUTPUT
RESET BELLOWS
(VENTED)
PROPORTIONAL
BAND ADJUSTMENT
PROPORTIONAL‐ONLY CONTROL
TO
RESET
BELLOWS
TO
PROPORTIONAL
BELLOWS
TO
NOZZLE
FEEDBACK
LINK
FEEDBACK
MOTION
DIRECT ACTION
QUADRANT
SUPPLY
PRESSURE
OUTPUT
REVERSE ACTION
QUADRANT
INPUT MOTION
FLAPPER DETAIL
OUTPUT PRESSURE
TO CONTROL DEVICE
RELAY
TO
NOZZLE
TO
RESET
BELLOWS
FLAPPER PIVOT
OUTPUT
RESET VALVE
SUPPLY PRESSURE
PROPORTIONAL‐PLUS‐RESET CONTROL
C0742
RELAY
PROPORTIONAL‐PLUS‐RESET CONTROL
Principle of Operation
Refer to figure 1 (proportional‐only control). 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
RESET
VALVE
RELIEF VALVE
WITH ANTI‐RESET WINDUP
SUPPLY
PRESSURE
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 1), an increase in process
differential pressure causes a decrease in output
pressure.
RELAY
RELAY
SUPPLY
PRESSURE
DIFFERENTIAL GAP CONTROL
5
Product Bulletin
34.4:4194
May 2013
Figure 2. Controller Construction Detail
4194 Differential Pressure Controllers
D200048X012
SET POINT
ADJUSTMENT
INPUT ELEMENT
(CAPSULAR
ELEMENT)
CONNECTING
Notes:
1 White portion of adjustment enables direct controller action; black portion enables reverse controller action.
2 For the process pointer.
W3612‐1
In addition to the proportional‐only (4194A) version, a
controller is available for proportional‐plus‐reset
LINK
Construction Features
control (4194B). In this controller, output pressure is
fed back to the reset bellows as well as to the
proportional bellows.
Simplified Relay Maintenance
A clean‐out wire provides a fast, easy means of
Anti‐reset windup is available on all controllers with
cleaning the relay primary orifice during service.
reset. Remote set point is available on all controllers.
PROPORTIONAL BAND
COVER
PROPORTIONAL BAND
ADJUSTMENT
ZERO ADJUSTMENT
SPAN ADJUSTMENT
1
2
2
The 4194S 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 counteracting it. This construction
causes the controller output to switch from full supply
pressure to zero pressure or vice versa.
The schematic diagram (figure 1) emphasizes detail of
construction variations between control modes. Refer
to table 1 for a complete description of type number
suffixes.
6
Pressure Protection for the Case
A rubber plug in the plastic case pops out to prevent
excessive pressure buildup from occurring inside the
case before structural damage can take place.
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).
4194 Differential Pressure Controllers
D200048X012
Product Bulletin
34.4:4194
May 2013
Figure 3. Typical Yoke Mounting
657
ACTUATOR
4194
CONTROLLER
67FR
FILTER
REGULATOR
MOUNTING
PLATE
W5661
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.
Figure 4. Controller Dimensions
REMOTE SET POINT
CONNECTION
TOP VIEW
130
(5.13)
330
(13.00)
31
(1.22)
1/4 NPT
4 HOLES
66
(2.56)
REAR VIEW
147
(5.80)
FRONT VIEW
LOW
PRESSURE
46A9765‐A
A5710‐1
260
(10.25)
HIGH
PRESSURE
BOTTOM VIEW
102
(4.00)
51
(2.00)
5/16 - 18
UNC‐2B
3 HOLES
(MOUNTING)
87
(3.44)
(10.04)
255
mm
(INCH)
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 4194 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.
Installation
The 4194 differential pressure controllers may be
shipped alone for a separate installation or for
installation on a control valve actuator. The controllers
can also be mounted on a pipe stand, on a wall, or in a
panel. When a controller is mounted on an actuator
and a positioner is not used, the controller will usually
be opposite the supply regulator as shown in figure 3.
If a positioner is used, the supply regulator can be
mounted on the actuator casing.
The controller must be installed so that the vent
opening faces down. Basic controller dimensions are
shown in figure 4. Dimensions for specific mounting
methods are shown in figure 5.
7
Product Bulletin
34.4:4194
May 2013
Figure 5. Mounting Dimensions
4194 Differential Pressure Controllers
D200048X012
92
(3.62)
HORIZONTAL PIPE
222
(8.75)
36A9757‐A
SIDE VIEW
62
(2.43)
95
(3.75)
VERTICAL PIPE
TOP VIEW
36A9759‐A
REAR VIEW
PIPESTAND MOUNTING PANEL MOUNTING WALL MOUNTING
B1473‐4
Ordering Information
When ordering, specify:
Application
1. Description of the service, such as throttling or
on‐off
2. Pressure range, composition, and temperature of
process fluid
3. Ambient temperature
84
(3.29)
63
(2.49)
161
(6.35)
TOP VIEW
13
(0.50)
62
(2.43)
14R
(0.56R)
236
(9.31)
306
(12.06)
13
(0.50)
36A9761‐B
(10.25)
13
(0.50)
260
152
(6.00)
62
(2.43)
REAR VIEWDIMENSIONS OF PANEL CUTOUT
mm
(INCH)
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.
Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance
of any product. Responsibility for proper selection, use, and maintenance of any product remains solely with the purchaser and end user.
Fisher is a mark owned by one of the companies in the Emerson Process Management business unit of Emerson Electric Co. Emerson Process Management,
Emerson, and the Emerson logo are trademarks and service marks of Emerson Electric Co. All other marks are the property of their respective owners.
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not
to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are
governed by our terms and conditions, which are available upon request. We reserve the right to modify or improve the designs or specifications of such
products at any time without notice.
Emerson Process Management
Marshalltown, Iowa 50158 USA
Sorocaba, 18087 Brazil
Chatham, Kent ME4 4QZ UK
Dubai, United Arab Emirates
Singapore 128461 Singapore
www.Fisher.com
E 1991, 2013 Fisher Controls International LLC. All rights reserved.
8
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