8/3/2019 Installation of P.G

http://slidepdf.com/reader/full/installation-of-pg 1/1

INSTRUCTIONS FOR THE INSTALLATION, OPERATIONAND MAINTENANCE OF TYPES 1125A/1128 &

1125/1127 DIFFERENTIAL PRESSURE GAUGES

1. Type 1125A/1128 – Gauge has adial with zero at top center. When thepointer is to the right of the zero it indi-

cates that the pressure at the righthand socket connection is greater thanthat exerted at the left and vice-versa.The gauge will not be damaged if thehighest pressure should shift from leftto right or vice-versa.

2. Type 1125/1127 – Gauge has theusual type dial, such as 0/30, 0/100,etc., with the zero at the bottom left.Pressure must be applied to the highpressure connection before the lowpressure is applied. It is important thatthe high pressure line be connected tothe right hand socket, (marked “H”).

3. General Information – The pres-sure gauge contains two bourdontubes, the free ends of which movewhen subjected to pressure. A gearmovement transmits the motion of thebourdon tubes to the pointer. A pres-sure gauge must not be subjected to apressure higher than the maximumworking pressure shown on the dial. Ifhigher pressures are applied, perma-nent distortion of the bourdon tube andinaccurate readings may result. Forbest service the gauge should operate

at approximately one half of the maxi-mum working pressure.(Example: A gauge with a dial range of 0-200 psi should operate at a working pressure of about 150 lbs. or less.) 

4. Installation – Pressure gaugesshould be mounted in a vertical posi-tion and free from vibration. The gaugesocket is equipped with standard sizewrench flats. These wrench flatsshould be used exclusively wheninstalling the gauge. Under no circum-stances should any force be applied to

the gauge case directly. Twisting of thecase may result in disturbing the cali-bration of the gauge.

5. Applications – For steam pressureapplications use a siphon. If the gaugeis installed above the point of measure-ment, install the siphon in the pressureline to the gauge. Install a shut-off cockbetween the siphon and the gauge.The siphon should be filled with waterto prevent steam from entering thegauge, otherwise the high steam tem-

perature may damage the instrument.If the gauge is located below the pointof measurement, the bourdon tube will

be filled with condensate and nosiphon is required. If the gauge isinstalled on a liquid pressure line, laythe piping so as to avoid vapor entrap-ment, otherwise readings may beincorrect. If possible, arrange for ventsat high points in the line to bleed offentrapped vapors.

6. Gauge Protectors and Dampeners– On installations which are subject tosevere pressure fluctuation, pulsationsand/or line shock, the use of snubbersor orifice pulsation dampeners is rec-ommended. The snubber is placed inthe line just before the pressure gauge.The pointer moves across the gaugescale at a rate which is proportional tothe pressure differential across the ele-ment. A moderate but smooth action isobtained, free from shock and pulsa-tion. Gauge failure due to pressureshock is eliminated. A simpler but lesseffective protective dampening deviceconsists of a restrictive orifice screw.The screw is available as an accessorywhen ordering the gauge.

7. Zero Adjustment – First remove the

bezel or retaining ring and glass face inorder to reset the pointer. There aretwo types of adjustable pointers. Themicrometer type is adjusted by holdingthe pointer firmly with one hand androtating the adjustment screw with asmall screw driver. The friction typeadjustable pointer is reset by holdingthe pointer firmly and rotating the slot-ted hub with a screw driver. Plain point-ers must be removed with a hand jack.On gauges equipped with plain point-ers, minor adjustments can be madeby rotating the slotted scale. When

resetting pointers to zero, it is impor-tant that there be no pressure in bothinlets.

 © 2007 Ashcroft, Inc., 250 East. Main Street., Stratford, CT 06614-5145, USA, Tel: 203-378-8281 • www.ashcroft.com

All sales subject to standard terms and conditions of sale. I&M008-10158 (84A493-01) 11/99 06/10