Dyna-Flo 5000 Parts list manual

Model 5000 Level Controller
Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
P-5000M0820A 1
Operation, Parts, and Instruction Manual
TABLE OF CONTENTS
General 2 Figure 7 - Controller Operation 10
Scope 2 Changing Controller Action 11
Specifications 2 Controller Maintenance 11
Unpacking 4 Replacing Gauges 11
Installation 4 Controller / Body Disconnection 12
Displacer Arm Installation 4 Seal Replacement 12
Controller to Vessel Installation 4 Re-Assembly 12
Electric Pilot Installation 5 Pneumatic Pilot Maintenance 13
Figure 2 - Wiring Diagram 6 Pneumatic Pilot Installation 14
Air Piping 6 Pilot Removal 14
Liquid Level Operation Adjustment 7 Electric Pilot Installation 14
Principles of Operation 8 Figure 8, 9, 10 - Displacer Diagrams 15
Controller Action 8 Figures 11 to 13 - 5000 Cross Section 16
Proportional Band 8 Figures 14 & 15 - Trunnion Assembly 17
Electric Level Switch 8 Figure 17 - Manual Test Apparatus 19
Figure 3 - Proportional Band Adjust. 8 Figure 18 & 19 - Electric Pilot 20
Figure 4 - Level Adjustment 9 Parts 21
Pneumatic Pilot Operations 9 Replacement Parts Kits 23
Snap (On/Off) Pilot 9 Model Builder 24
Throttle Pilot 10
N
TENT
S

Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
Model 5000 Level Controller
P-5000M0820A 2
Operation, Parts, and Instruction Manual
NOTICE These instructions are meant to be used with the Dyna-Flo 5000 Series Technical Bulletin as they refer to
Figures and Tables therein. If you do not have the Technical Bulletin, contact Dyna-Flo immediately,
or visit www.dynaflo.com
Each controller is factory checked. Check the calibration for the specific application, before a controller is
put into service.
GENERAL
The following instructions are to be thoroughly reviewed and understood prior to installing, operating or performing
maintenance on this equipment. Work on this equipment should be done by experienced personnel. Throughout the
manual, safety and caution notes appear and must be strictly followed, to prevent serious injury or
equipment malfunction.
SCOPE
The controller configuration and construction materials were selected to meet particular pressure, temperature, and process fluid
conditions. Some material combinations are limited in their pressure and temperature ranges. Do not apply any other conditions to
the controller without first contacting your Dyna-Flo sales office.
This manual is written to be a practical and useful guide maintaining the Dyna-Flo 5000 Level Controller.
! CAUTION !
To avoid personal injury or installation damage as a result of the sudden release of process pressure or the breaking
of parts, do not install the controller assembly where service conditions could exceed the limits stated in this manual
or on the equipment nameplates. Use government codes, accepted industry standards and good piping practices to
select pressure-relieving equipment for protection of your installation. It is also important to wear the proper
protective equipment when performing any installation or maintenance activity.
SPECIFICATIONS
Configurations
Controllers
•Throttling
•Snap-acting
Sensors
Pivotal movement of displacer arm is transmitted to the controller by a displacer-style liquid level sensor mounted to
the side of tank.
Standard Displacer Size
1-7/8” x 12 inches, 33 inches3(48 x 305 mm, 541 cm3).
Minimum Specific Gravity
Snap-Acting Controller
Minimum specific gravity (specific gravity differential for interface applications) 0.1.
Throttling Controller
Minimum specific gravity (specific gravity differential for interface applications) 0.1.

Model 5000 Level Controller
Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
P-5000M0820A
End Connection Maximum Pressure Rating
at 38oC (100oF)
MNPT 3,750 Psig (25,855 kPag)
150 RF 285 Psig (1,965 kPag)
300 RF 740 Psig (5,102 kPag)
600 RF 1,480 Psig (10,204 kPag)
600 RTJ 1,480 Psig (10,204 kPag)
900 RF 2,220 Psig (15,306 kPag)
900 RTJ 2,220 Psig (15,306 kPag)
1500 RF 3,750 Psig (25,855 kPag)
1500 RTJ 3,750 Psig (25,855 kPag)
3
Operation, Parts, and Instruction Manual
SPECIFICATIONS - Continued
Pilot
Pneumatic (standard)
•Snap - (on/off) 0-20 / 0-30 psig output.
•Throttle - (modulating) 3-15 / 6-30 psig output.
Electric (optional)
•SPDT - Explosion Proof.
•DPDT - Explosion Proof.
Supply Pressure Requirements
Snap-Acting Controller
• 3-15 or 0-20 psig output: 20-30 psig min.
• 6-30 or 0-30 psig output: 35-40 psig min.
NOTE
Do Not Use Supply Pressure Below 20 psig (138 kPag).
Maximum Sensor Operating Pressure
Conforming with Class 1500 pressure temperature ratings
per ASME B16.34 up to maximum pressure of 3,750 psig
(25,855 kPag).
Maximum Displacer Operating Pressure
3,750 psig (25,855 kPag).
Standard Pressure Gauge Indications -
(Supply and Output)
Triple scale gauges in: 0 to 60 psig / 0 to 0.4 MPa /
0 to 2,758 kPag.
Controller Connections
Output
1/4 inch NPT female (located on back of case).
Supply
1/4 inch NPT female (located on the back of case).
Case Vent
1/4 inch NPT (located on bottom of case),
vent screen apparatus included.
Vessel to Sensor Connection
1-1/2”, 2”, 3”, and 4” threaded (NPT) or flanged.
Sensor Temperature Limits
PVC Displacer
-29 to 80oC (-20 to 175oF).
HSN (Highly Saturated Nitrile) O-Rings
-40 to 204oC (-40 to 400oF).
Viton O-Rings
-26 to 204oC (-15 to 400oF).
316 SST Displacer
Non-limiting.
Operative Ambient Temperature Limits
For Controller: -29 to 204oC (-20 to 400oF)
SPECIFICATIONS - Electric Pilot
Output - proportional band adjustment
SPDT (single pole double throw)
7 - 55%
DPDT (double pole double throw)
20 - 150%
Switch Rating
UL and CSA listed: L96
15 amps, 125, 250, or 480 V.A.C.
1/8 Hp, 125 V.A.C.; 1/4 Hp, 250 V.A.C.
1/2 amp, 125 V.D.C.; 1/4 amp, 250 V.D.C.
Electric Pilot Model Number
SPDT (single pole double throw)
EX-Q
DPDT (double pole double throw)
EXD-Q
Certifications
Approvals: UL, CSA, ATEX (CE), IEC EX
Designations:
Div. 1 & 2, Class l, Groups B, C, & D
Div. 1 & 2, Class ll, Groups E, F, & G
ll 2 G; EEX d llB + H2 T6
Temperature Rating
-40 to 71OC (-40 to 160OF)

Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
Model 5000 Level Controller
P-5000M0820A 4
Operation, Parts, and Instruction Manual
UNPACKING CONTROLLER FROM
SHIPPING CONTAINER
Check the packing list against materials received, while
unpacking the controller. The Packing List describes controller
and accessories in each shipping container.
INSTALLATION
NOTE
If the Model 5000 Level Controller is to be installed
into a vessel that will be moved to another location
once assembly is complete it will be necessary to
remove the displacer arm (Key 42) before
transportation. Shipping the 5000 Level Controller
with the displacer arm installed in the vessel will
cause damage to the level controller.
1 Check to make sure that there are no obstructions inside
the vessel that would block the installation of the level
controller.
2 Locate the vessel wall sensor connection that will be used
to place the level controller at the appropriate control level
for operations. Once the appropriate connection is located
verify that it is equipped with the proper end connection.
3 Make sure that the desired vessel connection is capable of
supporting the weight of the level controller, if it is
inadequate it may be necessary to reinforce the
connection.
Displacer Arm Installation
(Reference Figures 8, 9, and 10)
NOTE
Make sure that the fulcrum bar pin (16A) is resting
inside the trunnion head groove. If the fulcrum
bar pin is not properly inserted into the trunnion
head groove, it may be difficult to install the
displacer arm (Key 42). Lubrication of the displacer
arm is unnecessary, the displacer arm o-ring is
already properly lubricated.
1Begin by inserting the 1/4” threads of the displacer arm
(Key 42) through the NPT connection as shown in Figure 11.
The threads of the displacer arm should protrude past the
trunnion head (Key 39). It may be necessary to re-position
the trunnion head periodically while inserting the
displacer arm.
2Install the 1/4” (star) lockwasher (Key 44) over the
displacer arm and snug it up to the trunnion head.
3Thread the 1/4” fine nut (Key 45) over the displacer arm
and tighten to 12 ft-lb.
Vertical Displacer Assembly
(Reference Figures 8, 9, and 10)
Assuming that the displacer arm (Key 42) has already
been correctly installed into the 5000 controller.
1 Thread the swivel assembly (Key 46) onto the end of
the displacer arm (Key 42). Hold the displacer arm in
place with a pair of pliers or vice grips and use a 1/2”
wrench to completely tighten the swivel assembly to
the displacer arm.
2Make sure the jam nut (Key 43) is threaded to the top
of the swivel bolt. Thread the displacer (Key 41) onto
the swivel bolt as far as possible. Tighten the jam nut
into the displacer using a 1/2” wrench.
Horizontal Displacer Installation
(Reference Figures 8, 9, and 10)
Assuming that the displacer arm (Key 42) has already
been correctly installed into the 5000 controller.
1 Remove the jam nut (Key 43) from the swivel bolt and
thread it onto the end of the displacer arm (Key 42) as
far as it will go.
NOTE
It may be necessary to hold the displacer arm
with a pair of pliers or vice grips when
performing the following steps.
2 Thread the displacer (Key 41) onto the displacer arm
until it makes contact with the jam nut.
3Using a 1/2” wrench, tighten the jam nut back into the
displacer.
Controller to Vessel Installation
WARNING
Use caution when moving an assembled controller,
stress applied to the displacer arm (Key 42) while
moving or carrying the controller can damage the
displacer arm and impair controller function.
Once the controller is completely assembled, insert the
displacer (Key 41) into the connection port of the vessel or
tank.

Model 5000 Level Controller
Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
P-5000M0820A 5
Operation, Parts, and Instruction Manual
Controller to Vessel Installation
(Continued)
NOTE
The functions of the 5000 Level Controller are
dependent on gravity. It is vital to the performance
of the controller that the bottom of the controller
case (Key 13) be parallel to the ground. See Figure 7.
NPT Connections
Follow good piping practices and screw the threads of the
controller body (Key 12) into the threads of the vessel
connection until the controller is tight enough to seal the
connection. Adjust the orientation of the controller so that
it is level (the bottom of the case is parallel to the ground)
by slightly loosening or tightening as necessary.
Flanged Connections
Before installing the controller be sure to inspect the flange
mating surfaces on both the controller and the pipeline
flanges. Also check the pipeline flanges for alignment.
Install line gaskets and studs, use a thread lubricant on
each end of the studs and tighten the nuts to the correct
torque specifications, evenly, using a crisscross pattern.
Sensor Check
Once installed into the vessel, check that the controller
displacer is able to move freely inside the vessel. Open the
case (Key 13) and rock the trunnion head (Key 39) to test
that the displacer arm (Key 42) moves without obstruction
inside the vessel. Ensure that the fulcrum bar pin
(Key 16A) remains seated in the trunnion head pivot hole
once the test is completed.
Electric Pilot Installation
General Information
The flame paths of Honeywell’s EX explosion-proof
switches cool exploding gases below the ignition
temperature before they reach explosive gases surrounding
the housing. The enclosed replaceable basic switch is
accessible when the cover is removed. EX series products
are NEMA 1 rated and therefore are not recommended for
use in areas when they will be subjected to liquid splash
EX series products are listed by Underwriters’ Laboratories
and CSA for use in hazardous locations NEMA 7, Class I,
Groups C & D, and NEMA 9, Class II, Group E, F, and G.
This includes vapors of ethyl ether, gasoline, petroleum,
alcohol, acetone, lacquer solvent, natural gas, and atmo-
spheres charged with grain dust, metal dust, carbon black,
coal, or coke dust. Select EX listings are also listed for
Class I, Group B (hydrogen) atmospheres. CSA requires
the following statement for Class I, Group B requirements.
DANGER
EMISSION OF HOT PARTICLES - Joint surfaces
must be thoroughly cleaned before closing.
Failure to comply with these instructions will
result in death or serious injury.
All EX series products comply with UL Standard: UL 894
and UL 1203, CSA Standard: C22.2 no. 25-1966, C22.2 no.
30-M1986. EX series products also meet NEMA 1 enclosure
requirements.
Select EX Series products also meet the European
Hazardous Locations Designation: Exd IIB + H2 T6
category II 2 G, KEMA 04ATEX2312X and complies with the
European Directive on Equipment and Protective Systems
Intended for Use in Potentially Explosive Atmospheres
(94/9/EC) commonly referred to as the ATEX Directive.
Compliance with the Essential Health and Safety
Requirements has been assured by compliance with
EN50014:1997, EN50018:2000 and EN50281-1-1:1998.
EX series products have a temperature range of -40OC to
70
OC (-40OF to 158OF), and when used within the
maximum voltage and current specified on the product will
have no heating problems.
Wiring Instructions
Use up to size #14 AWG solid or stranded wires to connect
to the pressure-type connector terminals. Use green wires
for ground leads, red wires for NC leads, blue wires for NO
leads, and black for common leads.
Cable Connection
The cable entry device shall be certified in type of
protection flameproof enclosure “d”, suitable for the
conditions of use and correctly installed. For ambient
temperatures above 60OC (140OF), cables and cable glands
suitable for a temperature of at least 80OC (176OF) are
required.
Conduit Connection
A certified sealing device in type of protection flameproof
enclosure “d”, such as a conduit seal with setting
compound shall be provided immediately to the entrance of
the enclosure.
For ambient temperatures over 60OC (140OF), suitable heat
resistant wiring and setting compound in conduit seal shall
be used. Blanking elements of unused apertures shall be
certified in type of protection flameproof enclosure “d”,
suitable for the conditions of use and correctly installed.

Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
Model 5000 Level Controller
P-5000M0820A 6
Operation, Parts, and Instruction Manual
CODE MICRO SWITCH CIRCUITRY ELECTRICAL RATING
“E” EX-Q
“D” EXD-Q
Single - Pole
Double - Throw
A
B
UL and CSA Listed:
15 amps, 125, 250 or 480 VAC
1/8 hp, 125 VAC; 1/4 hp, 250 VAC;
1/2 amp, 125 VDC; 1/4 amp, 250 VDC
Green - GROUND
BLACK - COM 1
BLUE - N. O. 1
BLUE - N. O. 2
RED - N. C. 1
BLACK - COM 2
RED - N. C. 1
Double - Pole
Double - Throw
UL and CSA Listed:
10 amps, 125 or 250 VAC;
0.3 amp, 125 VDC; 0.15 amp, 250 VDC
ELECTRIC PILOT SWITCH CIRCUITRY
Figure 2 Electric Pilot Wiring Diagram
INSTALLATION
(Continued)
Air Piping
WARNING
Property damage, environmental harm, and personal
injury can result from the use of a supply gas other
than clean, non-corrosive, oil and moisture free air.
The 5000 Level Controller vents supply gas through
the bottom of the controller, if hazardous or
flammable gas is to be used as the supply medium it
may be necessary to install a remote vent line.
Always ensure there is adequate ventilation is
present and that filters are receiving regular
maintenance when using the 5000 Level Controller.
1Be sure the operating medium supplied to the controller
meets the requirements of ISA Standard 7.0.01 and
supply pressure requirements (see Page 3). The use of a
supply medium that does not meet the requirements of ISA
Standard 7.0.01 may damage the controller.
2Connect the supply pressure to the 1/4” NPT SUPPLY port
on the back of the controller case (Key 13).
3Connect a line from the 1/4” NPT OUTPUT port on the back
of the controller case to the equipment being operated.
Remote Venting
CAUTION
Venting and vent lines should comply with local
and regional codes and regulations.
1Remove the vent (Key 14) if present at the bottom of
the case (Key 13). Venting occurs through the
adjusting thread (Key 11).
2Connect a 1/2” diameter pipe to the vent port, make
sure the pipe is free of foreign material and protected
against foreign material entering the line. The pipe
should have an adequate inside diameter and posses
as few bends as possible to reduce case pressure.

Model 5000 Level Controller
Dyna-Flo Control Valve Services Ltd.
Phone: 780 •469 •4000 Toll Free: 1 •866 •396 •2356 Fax: 780 •469 •4035 Website: www.dynaflo.com
P-5000M0820A 7
Operation, Parts, and Instruction Manual
CONTROLLER LIQUID LEVEL OPERATION
ADJUSTMENT (Reference Figure 4)
1Check that the supply pressure is set properly by checking
the supply pressure gauge (Key 52). Adjust the supply
pressure if necessary.
2Check that the displacer (Key 41) and displacer arm
(Key 42) are able to move freely inside the vessel by
rocking either the trunnion head (Key 39) or fulcrum block
assembly (Key 16), ensure that the fulcrum bar pin
(Key 16A) remains seated in the trunnion head pivot hole
once the check is completed. The displacer arm (Key 41)
should be reasonably level after checking the movement, if
not, adjust the spring adjuster (Key 27) until the fulcrum
bar assembly (Key 16) and displacer arm are in the
horizontal position.
3Loosen the fulcrum block thumb screw (Key 17A) and
position the fulcrum block (Key 17) about a half inch (0.5”)
from the center of the fulcrum bar (Key 16).
NOTE
It is recommended that controller level adjustments
be made within the required operating pressure
range. For example, if adjusting within a 3 – 15 Psig
range, do not adjust up to 17 Psig and then back into
the 3 – 15 range.
4Lower the liquid level in the vessel until it is either below
the bottom of the displacer or at the lowest required
operating point.
For applications involving liquid level interface, completely
submerge the displacer in the fluid with lower density (the
upper fluid). The fluid with the higher density (the lower
fluid) should be below the displacer or at the lowest
desired operating point on the displacer.
5Operation Specific Adjustment
Direct-Acting / Snap Pilot Controller
ATurn the spring adjuster (Key 27) until the output
pressure reaches full supply pressure.
BAdjust the spring adjuster until the output pressure
drops to zero Psig.
Reverse-Acting / Snap Pilot Controller
ATurn the spring adjuster (Key 27) until the output
pressure reaches zero Psig.
BAdjust the spring adjuster until the output pressure
rises to full supply pressure.
Direct-Acting / Throttle Pilot Controller
3 – 15 Psig
Turn the spring adjuster (Key 27) until the output
pressure is around 6 Psig then adjust the output
pressure down to 1 - 2 Psig.
6 – 30 Psig
Turn the spring adjuster (Key 27) until the output
pressure is around 8 Psig then adjust the output
pressure down to 2 - 4 Psig.
Reverse-Acting / Throttle Pilot Controller
3 – 15 Psig
Turn the spring adjuster (Key 27) until the output
pressure is around 10 Psig then adjust the output
pressure up to 16 - 17 Psig.
6 – 30 Psig
Turn the spring adjuster (Key 27) until the output
pressure is around 25 Psig then adjust the output
pressure up to 31 - 34 Psig.
Electric Pilot Controller
NOTE
The 5000E electric pilot behaves as a snap
(on/off) pilot, adjust liquid level operation
accordingly. Proper operational performance of
the electric pilot is tested in factory. Always
have a certified electrician perform all wiring
on the 5000E electric pilot controller.
AUsing the hex key provided (located in the bottom of
the controller case, Key 19) loosen the 4 socket cap
screws and remove the front panel of the electric
pilot.
BHave a certified electrician refer to the Electric Pilot
Switch Circuitry diagram (Figure 2) for wiring
instructions. Wiring should be fed into the electric
pilot through the nipple (Key 66) located on the
right side of the controller.
COnce wiring is complete, close the front panel of the
electric pilot using the 4 socket cap screws and the
hex key provided.
For more information refer to the Honeywell Explosion
Proof Switch Installation and Service Instructions
included with your 5000E Level Controller.

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Model 5000 Level Controller
P-5000M0820A 8
Operation, Parts, and Instruction Manual
PRINCIPLES OF OPERATION
The Series 5000 liquid level controller utilizes the “Force Balance System” (Figure 4). Force is applied to the fulcrum bar (Key 16)
distributed from the displacer-style level sensor (Key 42) using a series of levers and rods. The application of force to the fulcrum
bar is a direct result of the weight of the displacement type sensor. Forces acting on the fulcrum bar are balanced using a
compressed spring (Key 26) on one side of the bar. As fluid levels in the tank increase the buoyant force acting on the displacer
decreases its relative weight. Force applied to the fulcrum bar is, in turn, decreased resulting in the rotation of the fulcrum bar until
the forces are balanced again. A fulcrum (Key 17) mounted to the flapper shaft (Key 15) relays rotation of the fulcrum bar to the
pilot. Desired controller output can be regulated by adjusting the position of the fulcrum on the fulcrum bar. By using a Throttling
Pilot (Figure 6), a pneumatic modulating signal is achieved. A Snap-Acting Pilot (Figure 5) will result in a pneumatic on/off signal.
Electrical SPDT or DPDT output is attained by utilizing an electrical limit switch (Figure 17).
Controller Action
The installation of the flapper shaft (Key 15) determines controller action (Figure 7). When controller output is effected in the
same as liquid level, the control is considered “Direct-Acting”. When the vessel liquid level increases, the output signal will
increase and vice versa. For example, when the flapper shaft is positioned on the left hand mount, the result is “Direct-Acting”
control. “Reverse-Acting” control is achieved when change in liquid level results in a reverse effect to the pilot. As liquid level
increases, controller output will decrease. When the flapper shaft is positioned on the right hand mount, the controller is
considered “Reverse-Acting”.
Proportional Band
Proportional Band is the ratio of used displacer length versus the total length of the displacer. Proportional Band is used in order
to achieve a desired output signal (Figure 3).
For example if a 12” long vertical displacer is used with six inches of fluid level change in order to develop a required
output signal (ex: 3-15 psig), then the controllers Proportional Band is considered to be 50%.
Adjusting the fulcrum (Key 17) towards the pivot pin away from the retaining ring (Key 26) will increase Proportional Band
(decreasing sensitivity)(See Figure 3). By adjusting the fulcrum away from the pivot pin towards the snap-ring will decrease
Proportional Band (increasing sensitivity). Adjusting the fulcrum as described above (over any portion of the displacer) can
achieve a desired output signal such as 3-15 psig or 6-30 psig.
Electric Level Switch
The electric level switch uses the force balance principle to open and close an electrical switch in response to rising or falling
levels. Two standard switches are available, single pole double throw (SPDT) or double pole double throw (DPDT), both with
explosion-proof enclosure.
INCREASE PROPORTIONAL BAND DECREASE PROPORTIONAL BAND
Figure 3 Proportional Band Adjustment Diagram
17
15 16
17
15 16

Model 5000 Level Controller
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P-5000M0820A 9
Operation, Parts, and Instruction Manual
To Increase Level:
Turn the Spring Adjuster clockwise todecrease spring compression.
To Decrease Level:
Turn the Spring Adjuster counter-clockwise to increase spring
compression.
PRINCIPLES OF OPERATION
(Continued)
Activation
Adjust the spring compression (Key 26) by setting the spring adjuster (Key 27) to position the displacer arm. Move the fulcrum
bar by hand to check that the displacer arm is not resting against the vessel connection.
Figure 4 Liquid Level Adjustment Diagram
PNEUMATIC PILOT OPERATIONS
Snap (On/Off) Pilot Operation
Two valves compose the Snap pilot (Figure 5); one valve to
exhaust system pressure and one to admit supply pressure.
Flow of supply pressure gas into the pilot is controlled by the
ball (Key 47), force exerted by supply pressure holds the pilot
closed by forcing the ball on the pilot seat.
When sufficient force is transferred from the flapper shaft (Key
15) to the thrust pin (Key 58), the ball will snap off the seat,
releasing supply gas through the output port. As soon as the
ball snaps open, the seating end of the thrust pin seats and
simultaneously closes the exhaust port. Because the thrust
pin has a smaller seating area than the ball, the thrust pin can
remain seated against the force of supply pressure until force
from the flapper shaft (Key 15) subsides.
The “snap” action occurs as a result of differences in seating
area between the ball and thrust pin. Once force from the
flapper shaft subsides, supply pressure will unseat the thrust
pin and simultaneously seat the ball. As the thrust pin is
unseated it opens the exhaust port, venting supply gas.
Figure 5 Snap (On/Off) Pilot
26
27
27
26
SUPPLY
OUTPUT
SEATING END
EXHAUST
51 57
54
47
56
49
58
61

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Model 5000 Level Controller
P-5000M0820A 10
Operation, Parts, and Instruction Manual
PNEUMATIC PILOT OPERATIONS
(Continued)
Throttle Pilot Operation
A Throttle pilot (Figure 6) is similar to the Snap Pilot, both
consist of two inner valves. The difference between Snap and
Throttle being the use of a resilient diaphragm (Key 61).
A Force Balanced pilot is created utilizing the resilient
diaphragm in conjunction with valves ‘A’ and ‘B’. Force Balance
occurs as a result of supply pressure acting on the resilient
diaphragm equalizing force applied to it and force exerted by
the flapper shaft (Key 15).
In a Throttling Pilot the force applied by the flapper shaft to the
lower seat becomes relational to the force of output pressure.
Increasing the amount of force applied to the flapper shaft will
proportionally increase the amount of output pressure.
As force applied to the thrust pin (Key 59) changes, the pilot
compensates by unseating valve ‘A’ to increase output pressure
or by exhausting supply output at valve ’B’, resulting in a new
balance point. While the pilot is in balance, supply gas will not
flow. Figure 6 Throttle Pilot
Figure 7 Controller Operation Diagram
23 17 17A
16A
15
24 23
16
28
26 11
27
39
PIN B
16A
16
28
26 11
27
39
17A 2317
15
24
23
SUPPLY
OUTPUT
RESILIENT
DIAPHRAGM
EXHAUST
51 57
54
58
56
49
59
60
A
B
DIRECT ACTING REVERSE ACTING
GROUND
PIN A
PIN A
PIVOT
POINT
PIN B
PIVOT
POINT