PRECISION MANOMETER TEST SETS

"Precision with Portability"

Type 4 Portable Manometers

The 'oldest' instrument in our range, the Type 4 has proved its worth over nearly twenty years of steady development. Literally thousands are now in use throughout the world, and demand increases every year.

Based on two precision swivelling limb Micromanometers, the test set covers 0 to 5000 Pascals with a total of seven limb positions, and has a resolution considerably better than 0.25 Pascals on the most sensitive setting. A plate mounted inside the case gives details of the range covered by the various limb positions. The need for such a wide range of precision measurement is convincingly demonstrated by considering the example of a high pressure air distribution system, where the centrifugal fan can generate over 2000 Pascals in the plant room. In the smaller duct runs the static pressure may be only a tenth of this, and if it is necessary to investigate pressure losses around bends and transitions these could well be only 1 or 2 Pascals. To cope adequately with this range of pressures would normally require an untidy collection of at least 3 fixed range manometers!

But a test set should not be regarded as just a manometer. It is a complete system of equipment for on-site gas flow and pressure measurement, and the various accessories are vital complements to the basic gauge.

The Pressure Scales

The instrument is assembled with pascal (N/m2) scales, but loose, easily interchangeable scales in mm H20 and inches w.g. are included to suit the user.

Millibar scales are available to special order.

Velocity Scales

Velocity scales calibrated in metres per second and feet per minute are supplied. These particularly handy items, used with a pitot static tube, eliminate calculations when using the test set for measurement of ducted air velocities at or near 'standard' temperature and pressure (20°C/1013 mbar or 68°F/30 in Hg).

Velocity Calculator

For situations where the in-duct temperature and barometric pressure differ substantially from standard conditions, the slide-rule type air velocity calculator allows the operator to apply these two factors as a correction to the pitot tube reading. The true velocity can then be directly read from the slide rule.

Barometer

The aneroid barometer mounted on the panel of the Type 4 test set covers the range 785 to 1100 mbar and is also calibrated in cm Hg and in Hg.

Thermometers

Two mercury-in-glass thermometers are supplied, protected by tough plastic containers. They are of a length adequate to penetrate through most ductwork insulations and into the gas stream. One thermometer covers the range up to 400°C, whilst the other offers excellent accuracy from 0 to 60°C.

Connecting Tubing

Flexible PVC tubing ( 2 x 9 metres) is supplied in two contrasting colours. The grade and finish has been carefully selected to grip the push-on manometer connectors firmly whilst allowing rapid removal, and will stay safely in place at line pressures up to one atmosphere.

Although the connection to a test set can be of any convenient length, the 9 metres of tubing supplied as standard have been selected to provide a good balance between response time and damping. In many air distribution systems rapid fluctuations of pressure occur, and the damping effect of the tubing reduces the problem significantly when making sensitive velocity measurements.

Levelling Arrangements

The accuracy of a manometer, particularly at low angles of inclination is largely dependent on perfect levelling and this is achieved rapidly and precisely by means of screw-threaded feet on the main panel, adjusted in conjunction with built-in spirit levels.

The foldaway legs on the type 4 portable are individually moveable so that the set can stand square and firm even on rough ground. The underside of the cabinet is fitted with non-slip rubber feet to protect surfaces when it is used with legs folded.

Fluid Level Zeroing

This is achieved quickly and efficiently by rotating a conveniently situated panel-mounted knob.

Portability and Storage

Space is available behind the main panel for all the accessories and when closed up ready for storage or transport the whole outfit occupies less than 0.04 cubic metres and weighs only 11 kg (1.3 cubic feet/24lbs)

TYPE 4 SPECIFICATION

Laboratory Type 4 Portable Manometer

Although originally conceived as a portable instrument, the versatility and precision of the basic swivelling-limb manometer was such that inevitably the sets began to appear in laboratories and test-houses. Because of the vast breadth of possible application it became apparent that for laboratory use, some of the essential features of portable equipment were not required. The result of this was the introduction of a special laboratory version. In essence the lab version comprises the entire main panel of a standard portable test set, mounted on a steel plinth with rubber feet. The same levelling arrangements are employed between the panel and the plinth, which carries a plate giving details of the magnification factor and range covered by the limb in each of their different positions. The instruments are supplied with interchangeable pressure and velocity scales in Sl, Metric or Imperial units and spare fluid is included.

A comprehensive list of back-up accessories is available including straight or angled pitot static tubes from 2.3 mm diameter for use in small pipes, up to jointed (collapsible) tubes 5 metres long for use in giant ducts.

For details of ranges covered see specification of portable type.