Vacuum News

Cycle time is further reduced through ABAR’s patented “Square” shaped work zone, with temperature uniformity to better than 0.5 per cent of range. Heating is with resistive, low watt density, molyb- denum sheet heating elements providing a high radiating area. The dynamic heating elements and low thermal mass heat shields yield high-speed heat up within minutes, it is claimed.

The “Series 60” is a horizontal, front loading furnace. The full- opening front door allows maximum access to the 12 x 12 x 24-inch work zone. The vacuum vessel is constructed of type 304 stainless steel.

A graphic control centre contains all instruments and controls. All functions are sequential and fail safe. Flexibility is provided for manual and full automatic operation. Selector switches allow for partial pressure, or backfill and purge operation with process gas, hydrogen or inert gas.

Programmed temperature control is achieved with a standard recorder and with three-mode control form. To ensure the maximum temperature range being obtained an encapsulated toroidal, variable- reactance transformer was developed. Power shut-down is as low as 0.25 per cent with even temperature control from room temperature to the maximum of 3000°F. ABAR Corporation, Pennsylvania, USA Circle number 60 on Reader Enquiry Service card

Pressure transducers A new line of pressure transducers to measure gauge, absolute and differential pressures over a sensing range from vacuum to 20,000 lb/it? has been designed and produced by Schaevitz Engineering. Complete pressure measurement and control systems as well as individual transducers are available for measuring a wide variety of corrosive or non-corrosive gases and liquids.

High reliability is said to be achieved by the elimination of linkages, bearings and other friction-producing elements. The Schaevitz pressure transducers measure directly the movement of a Bourdon tube tip or a diaphragm by means of a linear variable differential transformer.

Basically, the line is composed of four models. The PY-I covers the range of 0 to 10 inches of water to 0 to 400 inches of water. It is a general purpose, industrial transducer for measuring gauge or differential pressures (absolute reference on special order) of non- corrosive liquids and gases. The PT-2 extends the pressure range from 0 to 15 to 0 to 500 lb/it?. When used with special O-rings, the PT-2 meets the requirements for many corrosive liquid and gas applications for gauge, differential or absolute measurements. The PT-3 is another pressure transducer for low-range measurements (0 to 10 to 0 to 400 inches of water). Its primary application is for measuring small pressure variations either above or below atmos- pheric. The PT-4 pressure transducer is a heavy-duty industrial-class gauge in a range of units from 0 to 25 to 0 to 10.000 Ib/inl. The pressure transd;cers are claimed to be suitable for a wide variety of measurements for missile and aircraft applications, for process industry measurements, for oil and gas processes and transmission and for utility requirements. Schaevitz Engineering, NJ, USA Circle number 61 on Reader Enquiry Service card

Low-cost electromanometer Consolidated Electrodynamics Division, Bell & Howell Limited, have introduced a Universal Electromanometer whose low price is said to make it possible for many industries to utilize this precision pressure-measuring system for the first time.

Electromanometers have been used primarily in space chambers, test stand facilities, environmental chambers and wind tunnels, but the lower price of this new instrument will make it possible for more companies in the petro-chemical and power-generation fields and facilities utilizing computer process control to take advantage of the instrument’s &-10-V analogue output, high accuracy and long-term stability.

The Universal Electromanometer consists of a servo-amplifier and a precision pressure balance. Additional components include precision pressure balances for wide pressure range capability, a multi-channel adapter for economical amplifier use and three rack- mount adapters for a choice of installation modes.

The standard Type 4-336 balance is available in ranges of f 5 lb/in*, *15 lb/in2 and &-60 lb/in”, both differential and absolute.

When the Types 4-332 and 4-334 balances are included with the

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Universal Electromanometer system from Consolidated Electrodynamics

Type 4-336, the group offers a total range capability between 1.5 and 10,000 lb/%.

The Universal Electromanometer is said to have an accuracy of 0.05 per cent and to require virtually no maintenance. Consolidated Electrodynamics Division, Bell & Howell Limited, UK Circle number 62 on Reader Enquiry Service card

Variable valve for microflows Veeco Instruments Incorporated have announced the Model P718 bellows-type microflow valve. The valve is constructed of 304 stainless steel with a Teflon seat for small, precisely variable through- puts. The valve has a micrometer-calibrated ad,just with 18 turns to

Variable valve for microflows

full open. The valve operates up to I50 lb/in* with gas or liquids, including corrosive or radioactive fluids. The device is also useful, it is claimed, for vacuum applications. For high-temperature opera- tions, Model P719 is available.

The valve is made by Socomeco of France. Veeco Instruments Incorporated, NY, USA Circle lumber 63 on Reader Enquiry Service card

High temperature wrap-around heater Kassen Associates Incorporated have introduced a new precision, high-performance industrial heater that can supply temperatures up to 450°C. The heater is of aluminium and stainless steel construction with an outer insulation of silicon fabric, engineered for continuous duty operation in any orientation. It is equipped with a 6-foot heavy-duty cord and earthed plug for operation at 115 V, AC or DC. The heater is 4$-inches in inside diameter, 9-inches long and has open ends.

The heater, designated the model S-999, is said to have been

Vacuum News

I This chamber is said to be capable of freeze-drying 15 lb of “fresh product”. It has a product shelf area of 660 in”, having three separate product trays each separated by heater platens. Platen temperatures are controlled by an electronic temperature regulator to 4~0.25% Temperature balance between platens is by way of energy regulators.

Refrigeration is by a 1; hp accessible-type condensing unit utilizing R502 as the refrigerant. Vacuum is produced by a 150 litres/min pump and measured by Pirani and capsule gauges.

This machine is completely self-contained and mounted on casters for ease of re-location.

The company plans to manufacture four models in the laboratory- pilot plant range. Cutler Refrigeration, Australia Circle number 6.5 on Reader Enquiry Service card

Liquid-nitrogen replenisher Now available from Mullard is an automatic replenishing system that is said to enable a constant level of liquid nitrogen to be main- tained in Dewar cold traps or almost any other type of nitrogen cooling system in general use. By using the new replenisher, vacuum

High-temperature wrap-around heater

successfully used on vacuum system components including regenera- tion of molecular-sieve materials in sorption pumping, bakeout of valves, electrical feed-through, linear and rotary motion feed-through mechanisms and tubing and pipe tabulations. Kassen Associates Incorporated, Cal~ortda, USA Circle number 64 on Reader Enquiry Service card

Freeze-dryer The photograph below illustrates a new freeze-dryer, designed by the Commonwealth Scientific and Industrial Research Organisation, Australia, built by Cutler Refrigeration of Sydney, Australia and delivered to the Australian Department of Primary Industry, Brisbane.

sorption pumps in ultra-high-vacuum systems or the liquid-nitrogen traps of diffusion pumping equipment used in many manufacturing industries may now be left operational overnight or even for a com- plete weekend without attention.

The replenisher comprises a simple, heat-opersited pumping

I

arrangement controlled by a level-sensing thermistor circuit. Pumping is effected by pressure build-up in the nitrogen reservoir. In operation, the thermistor temperature will rise when the liquid-nitrogen level drops. The change in resistance of the thermistor actuates the transistorised control unit, closing the normal reservoir vent and switching on a heater in the reservoir. The resulting pressure build-up in the reservoir forces liquid nitrogen through a transfer tube to the cold trap. When the correct cold-trap level has been re-established, the thermistor temperature drops, causing the control circuit to revert to its original condition.

As an added refinement, two thermistors are fitted in the detector I head. The distance between them is adjustable to allow the level of

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