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Pressure sensors, monitors and controls: product lines reviewed.



Provides pressure sensors and controls for complete process control. UL-recognized control systems include full pressure/vacuum sensor, monitor, control and recording capability. In addition, company distributes a wide selection of pressure controllers, monitors and recorders.



Offers a complete line of pressure transducers and transmitters for industrial monitoring. Pressure ranges from 3 to 5000 psi are available, along with a variety of input/output configurations. Millivolt, voltage, frequency and 4-20 mA outputs are available on standard products. Complete media isolation is achieved on company's Model 88 series transmitter with stainless-steel wetted parts.


Offers its BTL linear displacement transducers for use on injection molding machines to monitor closing of molds, location of feed screw, and the position of ejectors. The transducers reportedly provide continuous position feedback and employ a noncontact method of measurement suited to open-or closed-loop operation with continuous cycling. Accurate to 0.001 in. (depending on application), units are said to be insensitive to jolts and vibrations while producing an absolute measuring signal.


Supplies piezoresistive, piezoelectric and RTD-based analog and digital pressure and temperature transducers.

* APT and DPT lines of piezoresistive pressure transducers are recommended for injection molding.

* New switching transducer is a pressure sensor that provides continuous analog output, together with on/off actuation at a programmed setpoint.

* New CFT-7 tiebar force and strain transducer is reportedly unique in that it can be mounted in a smooth, nontapped hole in the tiebar, because of a proprietary internal mounting insert. CMC plans to introduce soon a "four-in-one" tiebar balancing gauge, which senses and displays stress and strain on all four tiebars simultaneously to aid in balancing.


Manufactures pressure transmitters for ranges from 0 to 40 in. [H.sub.2]O to 0 to 3000 psi. Process connections as small as 1/2 in. npt are available, as are antiflanges in various sizes.


Offers a complete line of melt-pressure transducers, pressure indicators and controllers for standard or special applications in extrusion or injection molding processing. Products include:

* PT420 high-accuracy pressure transducer for critical pressure and temperature measurements, [+ or -] 5% accuracy in ranges to 30,000 psi, rigid- or flexible-stem configurations, and integral thermocouple model.

* PT460 economical pressure transducer with reliable, cost-effective pressure measurement, [+ or -] 1.0% accuracy in ranges from 500 to 30,000 psi, rigid- or flexible-stem configurations, and integral thermocouple model.

* PT460 amplified-output pressure transducer for long-distance transmission without noise interference; easier interface with PLCs or computer-based extruder control systems and 4-20 mA, 2-wire; 0-5 VDC, 4-wire; 1-6 VDC, 3-wire; 0-10 VDC, 4-wire; or 1-11 VDC, 3-wire outputs.

* PT240 process industry pressure transmitters for high-temperature applications, including synthetic fiber spinning and melt extrusion; Factory Mutual approved for Class 1, Division 1, Groups B, C and D hazardous areas; flange-mount or threaded-mount; and 4-20 mA and voltage outputs.

* PT460XL enhanced-performance pressure transducers with extra-thick sensing diaphragm for improved corrosion resistance, high accuracy up to 30,000 psi and 750 F, and zero shift due to temperature change.

* PT130 hydraulic-pressure transducer which detects shot-to-shot variations and irregularities during feeding, measures injection ram and clamp, encompasses contoured sensing diaphragm for greater accuracy, repeatability and fatigue strength, and has 3 mV/V, 5V, 10V or 4-20 mA outputs.

* PT465XL nozzle-pressure transducer with flexible armored cable for longer life, ability to measure actual melt pressure within an injection molding machine or hot runner, 8-mil-thick flush diaphragm, and accurate measurements up to 30,000 psi and 750 F.

* PT449 direct-cavity pressure transducer, which mounts flush within the cavity, displays high-accuracy up to 400 F mold and 600 F melt temperatures.

* Indirect cavity-pressure transducers measure pressure from behind an ejector pin or sensing pin, install easily in space-restricted areas, with ranges from 0-50 to 0-2200 lb and up to 450 F.

* Mechanical/electronic melt-pressure gauges provide reliable, local indication on plastic/rubber extruders, easy-to-read gauges, and resistance to vibration.

* UPC660 Pressure Controller with microprocessor-based, 1/4-DIN plug-in design; auto/manual mode, dual programmable alarms fully-adjustable PID control, dual LED displays setpoint, process condition, deviation from setpoint percent of power output, selectable MA/VDC control output, serial communications available.

* UPR690 Pressure Indicator with microprocessor-based, 1/4-DIN plug-in design; analog and digital LED display, low- or high- pressure alarms, optional third alarm and serial communications, pushbutton transducer calibration, selectable voltage or current auxiliary output.

New from company: ST184 Smart Transmitter, reportedly the first "smart" melt-pressure transducer, is a micro-processor-based, two-wire transmitter that is said to be capable of measuring pressures up to 10,000 psi at temperatures up to 500 F with extreme accuracy - better than 0.1%. The key to the unit is the microprocessor embedded in the transducer housing, which enables users to employ a hand-held communicator to re-zero and re-span the unit, as well as perform diagnostic procedures on the transducer.


Manufactures in the U.S. Model 818 PID melt-pressure controller for extrusion market. Controller accepts a 350-ohm, strain-gauge input and incorporates its own transducer power supply. Front panel features an auto/manual station and high-visibility dual displays for simultaneous viewing of measured value and setpoint. A simple front-panel procedure calibrates the input transducer. Digital or analog communications are available, in addition to two-alarm outputs. Separate rate limits can be applied to both setpoint and output signals. Instrument is fully configurable to facilitate implementation by OEM and enduser.


Offers plastic-melt pressure transducers/transmitters. Transducers feature a blend of integrated circuit and mechanical design technology. Filled transducers provide 0.5% FSO accuracy and a diaphragm that is 25-50% heavier than usual. Units have completely encapsulated electronics and an all-welded stainless-steel housing with permanent identification on an etched stainless nameplate. For more demanding applications ruggedized models 136, 137, 138 and 139 provide a heavier diaphragm.



Manufactures transducers and instrumentation. Pressure-transducer instruments are available in accuracies of 0.5% or 1.0% and have stem lengths in either 6 or 12 in. and pressure ranges from 1000 to 20,000 psi. Options offered include metric-thread dimensions, corrosion- and abrasion-resistant diaphragms, and waterproof wiring.

Analog- and digital-pressure indicators are available with "D" option, which is used for triggering an alarm relay. Standard voltage outputs are: 0-1, 2, 5 and 10 volts d-c. Optional 4-20 mA output is available on all indicators.


Offers extrusion controls and sensors to control extruder drive and barrel temperatures, gear pump and screen-changer. The VM2 viscosity sensor uses two separate pressure-measuring diaphragms - one at the end of the sensor, pointing radially toward the center of the melt stream (as in standard sensors), and a second one on the side of the sensor tip pointing upstream along the melt-flow axis, sensing the motion of the material. Unlike standard sensors, this method distinguishes increases in melt pressure resulting from screen blockage (e.g., from true viscosity changes). Also available is the DMV 1000 microprocessor-based melt-pressure amplifier that is said to be compatible with many different transducer systems.


For extrusion throughout stabilization by closed-loop feedback control of pressure at the die, company offers a line of microprocessor-based pressure controllers. Mounted in a convenient plug-in 1/4 DIN module they feature read-out of pressure on large LED numerals, plus separate LCD display to allow any calibration and mode changes, and are available in both single-channel and differential-pressure control forms. Differential-pressure control is particularly useful in the control of melt pumps, where it can greatly increase metering accuracy, and is also useful for control of continuous screen changers.


Company's Industrial Automation & Controls Div. offers a full line of ST 3000 Smart Pressure Transmitters, which are available for process applications where flow, liquid level, gauge pressure and absolute pressure, and even vacuum must be precisely measured and controlled.

With a Smart Field Communicator (SFC), the ST 3000 can be remotely configured, re-ranged, diagnosed and can display process values. A 400:1 turn-down ratio allows one model ST 3000 to be used for many applications. In its analog mode, the ST 3000 is accurate to [+ or -] 0.1% of span. In its DE (digitally enhanced) mode, the ST 3000 is accurate to [+ or -] 0.75% of span or [+ or -] 0.15% of reading, whichever is smaller.


New Terwin 1100 series pressure transmitters from Terwin Instruments Ltd. of England are designed for plastic, rubber and food extrusion. They have a two-wire 4-20 mA output and incorporate company's proprietary force-rod transducers, which are constructed entirely of stainless steel and use no mercury or other toxic substances. Temperature stability is claimed to be better than 0.005% per 1/2 F. Pressure ranges are available from 500 to 30,000 psi and temperature's capability to 842 F. All have abrasion-resistant diaphragms, come in a range of stem lengths, and reportedly conform to NEMA 12 standards for protection against moisture and dust.

IN USA markets Terwin's complete line of extruder pressure/temperature instrumentation.


Manufacturers high-temperature melt-pressure transducers for the extrusion process. A complete instrumentation line is also offered to monitor and alarm the on-line pressure. Company also manufactures self-contained pressure gauges for extruders to replace grease gauges. High-level outputs (4-20 mA, 0-5 volts d-c, 0-10 volts d-c) are available on all melt-pressure transducers.



Offers a broad line of pressure transducers for industrial and testing applications from Wika of Germany. Four types of transducers are all carried in stock for 24-hour delivery. The ST-420 line ranges from vacuum to 0-15,000 psi with either 4-20 mA or 0-5 volts d-c output. The ST-420FL line of flush diaphragm transducers, for use in tank level or measurement of slurries or viscous media, range from 0-100 in. WC to 0-8000 psi. The ST-420SM submersible pressure transducers measure pressure from 0-100 in., WC to 0-250 psi with a 4-20 mA electrical output. The ST-420SM units come with a 40 ft cable and eyelet for retrieval. The fourth line, the ST-420IS line, is the newly introduced intrinsically safe transducer. These intrinsically safe units range from 0-5 psi to 0-5000 psi. All units have overall accuracy of 0.25% of full scale. The lower pressure sensors are piezoresistive, and higher pressure sensors are thin-film. Amplifier and other sensitive components are encased in silicone gel for protection against contamination and vibration. Absolute ranges are also available.


Company reportedly manufactures the only piezoelectric (quartz) transducer for measuring cavity pressure in a thermoset and thermoplastic injection molding process. It is said to have the smallest in-cavity sensing device (2.5 mm).

Company offers both direct and indirect measuring systems. Mold temperatures are sensed with a J-style thermocouple. Transducers that measure bar strain ensure even clamp loading and prevent tie-bar breakage.

In addition to transducers, company carries a full line of electronic-charge amplifiers to interface transducers to injection molding machine controls. Charge amplifiers can be used to control the molding machine or to give 0-10 v outputs for monitoring and data acquisition.

Company also intends to market software for SPC and a piezoresistive unit for measuring extruder melt pressure.


Manufactures pressure transducers, monitors and controllers, and machine upgrade kits for injection molding. Products include:

* T-400 series mold-cavity pressure transducers feature a ruggedized universal design with removable cable, a range from 0 to 2000 lb, 0.1% repeatability, and compatibility with slide or button application.

* T-202 peak-reading digital hydraulic pressure gauge features one psi resolution, 0 to 5000 psi range, and quick disconnect for portability.

* T-2015 digital transducer signal conditioner features peak-reading capability, setpoint logic, and autozero for nulling preload before injection.


Designs and manufactures pressure sensors and linear position sensors. Pressure sensors are built to perform in demanding environments in ranges 0-0.5 to 0-10,000 psi.

Company's contactless linear position transducers, providing absolute position measurement of displacement up to 10 ft, measures the position of moving machine parts such as hydraulic cylinders and injection molding machines. The probe is pressure sealed to operate in hydraulic fluids up to 3000 psi. Other sensors offered include dimensional gauging probes, rotary position sensors, velocity sensors, accelerometers, inclinometers, load cells and supporting electronics.



Company's Super TJE pressure transducer employs a "square-bridge" design whose input and output resistance is made to equal 350 ohms [+ or -] 1.5%. An outer-shell design enables unit to achieve superior stability (0.0015%/ [degrees] F temperature compensation) and is calibrated in a separate production facility to ensure superior accuracy, temperature compensation, and reliability.

Available in gauge or absolute types and in ranges from 30 to 3000 psi, the Super TJE utilizes select electronics to insure 0.05% accuracy and has a welded stainless-steel construction to ensure long life. Units provide an unamplified output signal of 3 mv/v and optional internal electronic amplified signal of 0-5 volts d-c or 4-20 mA and has a 1.7 in. diam. and is 3.25 in. long with amplifier.


Offers its Series 400 polymer extrusion melt-pressure transducers, which employ a patented and reportedly unique silicon-on-sapphire design that incorporates an integral strain-gauge bridge and sensing diaphragm directly exposed to polymer melt at operating temperatures up to 750 F. The transducers are said to be extremely durable. The sapphire diaphragm's extra thickness and hardness resists highly abrasive-filled materials and is said to provide 0.25-millisec response times. Units are available in ranges from 500 to 15,000 psi, lengths of 6 or 12.5 in., with English or metric threads, and are interchangeable with existing transducers.


Company's DACS (Data Acquisition & Control Systems) Division manufactures the 500 series datalogger, data acquisition, process control, software and complete system products. The DACS Division offers both turnkey systems and stand alone products. System sizes vary from 8-channel systems to 96-channel hot-runner controls, to 2300 channel PlantWide SPC production quality monitoring systems. Equipment connects to most industrial sensors, transmitters, transducers, or signal condition devices. Most products can be set up at the instruments front panel or can be remotely programmed from a PC. Scale, offset, process alarms, alarm displays, alarm outputs, control outputs and other functions are standard.


Offers a broad range of stainless-steel and brass pressure gauges for plastics processing.

* Process gauges, accurate to 0.5% of full scale; 4-, 6- and 8-in. diam; copper alloy, brass, and stainless wetted parts; 1/4-in. or 1/2-in. npt bottom or lower back connection.

* Industrial gauges; 1% F.S.; 3-, 4-, 6- and 8-in. diam.

* Severe duty; liquid fillable; 1% F.S.; 2 1/2- and 4-in. diam.

* Small gauges; 1 1/2 in. and 2 in.; stainless-steel case with brass or stainless-steel internals.

* Small gauges; 2 in. and 2 1/2 in.; all stainless steel with one-piece polycarbonate screw-on bezel and lens.

* Low-pressure gauges; 4- and 6-in. diam.; capsule or bellows element; provide combination of ranges from 10 in. [H.sub.2]O to 120 in. [H.sub.2]O; 1/4 in. NPT bottom or lower back connection.

Company also offers duplex, receiver, precision, differential-pressure, and transmitter gauges.



Offers a line of all-welded, all titanium, miniature flush mount (3/8-in. diam.) and 10-32 port pressure transducers for oceanographic, hydrologic, hydraulic, HPLC (chromatography), weighing and general purpose measurement from 25 to 5000 psi. Companion 3 1/2 and 4 1/2 digit displays are provided in panel mount DPMs and bargraphs.

WIKA See International Pressure Products.
COPYRIGHT 1991 Gardner Publications, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:1991-1992 Manufacturing Handbook and Buyers' Guide
Publication:Plastics Technology
Date:Jul 15, 1991
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