Pneumatic Indicating Controllers

MODEL 40 PNEUMATIC INDICATINGCONTROLLERS & TRANSMITTERS

Quality, flexibility, accuracyand dependability.

Indication of measuredvariable.

A non-bleed, high capacityrelay with excellent stabilityand fast response.

Easy field calibration.

Broad selection of controlmodes; proportional plusreset, proportional plus resetplus rate, differential gap andtwo position bypass.

Wide selection of processmeasuring elements for pres-sure, temperature, differentialpressure, flow and level.

Large, easy-to-read blackon white dial for maximumresolution.

Case and door with epoxypowdered finish for environ-mental protection.

Model 40 Pneumatic Controllers auto-matically position a valve or other finalcontrol element to maintain processpressure or temperature at the desiredset point. As receiving controllers, theycan control any process variable trans-mitted as a pneumatic signal.

Standard models have proportionalband adjustments for controlling pro-cesses where load changes are infre-quent and can be corrected by the

manual reset feature, standard in everycontroller. By a simple screwdriver ad-justment, the standard proportional con-troller can be changed to two-positioncontrol action with adjustable differentialgap.

Model 40 Controllers are also availablewith up to 300% proportional band withautomatic reset and rate action (for pro-cesses with frequent load changes ortemperature processes with transfer

lags). They not only satisfy ordinary con-trol requirements, but are equally profi-cient in controlling processes with unfa-vorable characteristics, particularly intemperature regulation.

The basic instrument is also availableas an indicating pneumatic transmitter.Mounted close to the point of measure-ment, it transmits an air pressure signalproportional to the measured variable toanother indicator, recorder or controller.

D E S C R I P T I O N

F E A T U R E S

U.S. GAUGE • PMT PRODUCTS 820 Pennsylvania Blvd., Feasterville, PA 19053 U.S.A. • TEL: (215) 355-6900 • FAX: (215) 355-2937 • www.ametekusg.com

EFFECTIVE: 11/98 SUPERSEDES: 11/90

BULLETIN DB-40

P N E U M AT I C C O N T R O L L E R S & T R A N S M I T T E R S

U.S. GAUGEPMT PRODUCTS

C O N T R O L A C T I O N SPROPORTIONAL CONTROL—Thisaction provides an output signal propor-tional to the measured variable. Standardoutput pressure for controllers is 3-15 psiwith proportional band adjustment of 1 to100%. Band widths to 200% are also avail-able. Outputs of 6-30 psi and 3-27 psi areoptional. An index on the chassis plate of acontrollers permits precise setting of bandwidths. Proportional control alone is idealfor process pressure regulation service(upstream) or relief service (downstream).Standard proportional controllers are rec-ommended for most batch processes anda great many continuous processes whereload changes are small or infrequent.

PROPORTIONAL PLUS RESETACTION—When load changes are largeor frequent and the process will not toler-ate quick or drastic changes in controlaction, automatic reset is desirable toavoid excessive offset from the desiredvalue under wideband proportional control.The feedback diaphragm on the standardproportional controllers is replaced with areset assembly. A standard reset needlevalve offers a wide range of settings from0.03 to 5.0 minutes per repeat (optional .03to .5 minutes repeat available).

PROPORTIONAL CONTROL PLUSRESET AND RATE ACTION—The func-tion of the three mode controller is to elimi-nate offset, increase stability and reducestabilization time. This type of controller isused to closely control a process thatdoes not involve sudden upsets and wideproportional band settings. This unit isideal for temperature control of heat ex-changers, especially when a thermowell isused. Not designed for flow or pressureapplications. Reset and rate times arestandard at .03 to 5.0 minutes per repeat.

DIFFERENTIAL GAP ACTION—This is a two-position control mode standard in all Model 40 Proportional Controllers. The output pres-sure of the controller remains at maximum (20 psi standard) or minimum (0 psi) until the controlled measurement crosses a band or gap,causing the output pressure to reverse. The measured variable must then span the gap in the opposite direction before the output signal isrestored to the original condition. Differential gap action is useful in controlling pumps and compressors to prevent excessive on-off cycling.Several controllers set in sequence with overlapping bands may be used for cutting in several stages of a process successively and cut-ting them out in reverse order. Gap may be adjusted over the full range of the proportional band.

Proportional plus rate plus reset.

Model 40 Pneumatic Controllers

PROPORTIONALBAND ADJUSTMENT

FEEDBACKDIAPHRAGM

PROPORTIONALBAND ADJUSTMENT

RESETKNOB

RESETASSEMBLY

PROPORTIONALBAND ADJUSTMENT

RESETKNOB

RATEKNOB

RESET/RATEASSEMBLY

Capacity Lag Large Tank Found when there is anappreciable inventory or storageof the controlled medium

Level control in processretention tanks. Batch heating.

Transfer Lag Found when it is necessary toforce corrective action through aresistive element before itaffects the process.

Temperature control using aheat exchanger, especiallywhen a thermometer well isused.

Instantaneous Response Found when the manipulatedvariable is the same as thecontrolled variable or if they aredynamically equal.

Flow control, pressure control orliquids in pipelines or othervessels completely filled with theliquid.

Proportional plus reset.

Velocity-Distance Lag Found when the measuringdevice is downstream of thepoint of corrective action. Equalsthe separating distance ÷ thestream velocity.

Any process control requiringreaction time beforemeasurement. Any analyticalvariable control loop where thesampling system producesdead time.

Proportional plus slow reset (donot use rate). Eliminate deadtime if possible.

TYPE OF PROCESSDESCRIPTION EXAMPLES

CONTROLDYNAMICS REQUIRED

On-Off differential gap.

G U I D E T O C O N T R O L L E R S E L E C T I O N

F E A T U R E S

ADJUSTING WRENCH—1/4" x 1/8" stored ondoor can be used for allnecessary adjustmentson movement, pointersand nozzle.

SHROUD—Anodized aluminum shroudbrightens dial area for greater visibilityunder adverse lighting conditions.

PROPORTIONAL BAND ADJUSTMENT—Adjustable by screwdriver within 90 degreequadrant indicated on dial. For availableband widths and control options, consultfactory.

RELAYS—Non-bleed, high capacity relay is standard on all controllers. Bleedrate of less than 0.1 SCFM at 9 psi output and the capacity to deliver over 3.0SCFM result in exceptionally stable, fast responding controller. May be easilydismantled for cleaning without disturbing factory-set adjustments.

NOZZLE—Specifically designed forincreased stability of pneumaticcircuit, nickel silver nozzle can beturned on turret to reverse controlaction. 0.018" bore.

ORIFICE—Sapphire0.008" bore with integralpushbutton cleaner.

SET-POINT ADJUST—Internal,external or remote available.

CASE—Cast aluminum with dustledge and deep weatherproofgaskets, captive stainless hinge pinsand latch shaft, rectangular glass.Optional gas-tight construction withcase tapped for 1/2" pipe vent. Forhigh-pressure applications, shatter-proof glass and blowout grommetsare available.

PROCESS INDICATIONS—Black adjustable pointer on31/2" precision gauge dial(7" scale length). Readilyadjusted to compensate forhydrostatic heads in piping.

FINISH—Die-cast alumi-num with semi-flat blackpowdered epoxy finish.

MOVEMENT—Micrometer rangeadjustment plus adjustable sectorand link for scale-shape calibrationof both indicating and set pointmechanisms provide easy fieldcalibration.

DIAL—Large, easy-to-read blackon white dial face with full 7"scale for maximum resolution.

S P E C I F I C A T I O N SINDICATION ACCURACY—1% middle halfof scale, 1½% remainder. Most ranges maybe calibrated to ½% accuracy at nominalextra charge.

SENSITIVITY—Less than 0.1% of full scaleat 100% Proportional band.

FREQUENCY RESPONSE—Flat to 400CPM with 200 ft. of ¼” tubing and 1.2 cubicinch capacity. Flat to 120 CPM with 18’ 3/8”tubing and 200 cubic in. capacity.

CONSTRUCTION—Moving parts aredesigned as light as possible to keepfriction and inertia forces low. This designalso results in higher resistance to vibrationand shock.

MOUNTING—Surface, flush panel, pipe-supported or valve-mounted. Fordimensions, see page 13.

AIR SUPPLY—20 psi for 3-15 psi range; 35psi for 3-27 & 6-30 psi range; 65 psi for 12-60 psi range. A filter and dripwell arerecommended ahead of each controller toensure clean, dry air supply. May beoperated on natural gas or bottled CO2.

CONNECTIONS—Standard backconnections are ¼” female NPT.

MEASURING ELEMENTS—A wide rangeof precalibration measuring elements forpressure and temperature are detailed onpages XX and XX.

MODULAR CONSTRUCTION—Each ofthe following components may be removedwithout disturbing the other components:control chassis complete, precalibratedelements, feedback assemblies, completerelay units, or supply gauge only, or nozzlefeed orifice and cleaner assembly only, orrelay diaphragm housing and valve stemonly-output gauge and tubing.