Ashcroft 1305DMH-700 Manuale di installazione e manutenzione - Pagina 8

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One Weight Box:

10 inch (25 cm) width; 10 inch (25 cm); 10 inch (25 cm)

height

Storage space dimensions are larger than actual size of

tester carrying case and deadweight carrying case by

approximately _ inch, (1.3 cm), in order to facilitate ease of

handling in storage.

Note: For catalog numbers 1305D, DH-100, 1305DM,

DMH-150, 1305DB, DBH-700 and 1305DA, DAH-

700 allow storage space for two weight boxes.

3.3 Operation 1305D

3.3.1 Piston and Cylinder Selection

The 1305D Tester is a dual range device in that most

-models utilize two interchangeable piston and cylinder

assemblies for measurement of pressure throughout the

entire range. Each piston and cylinder assembly has a

minimum and maximum operating range. First, determine

what pressure points need to be measured and select the

appropriate assembly. The pressure range of the assem-

blies is shown in Table 2-1. When priming the pump the

high pressure piston and cylinder assembly should be used.

3.3.2 Priming the Pump

The offset pipe (64 or 66 Figure 2-1) should already be

secured in place and the reservoir should contain the op-

erating fluid (refer to Installation Section 3.2).

Close the release valve (37) by turning it clockwise and

open the air vent by loosening the filler plug (35) a few

turns. The shuttle valve (51) should be pulled outward

from the pump body, the end of the knob approximately

even with the edge of drip pan. In this position the high

volume displacement mode is selected and the pump is

self-priming. Operate the pump handle several times using

full strokes, until you see fluid appear in the outer pump

body outlet.

The cone seat (82) is located in the base of the out-

er-pump body outlet and serves as the sealing surface

between the bottom of the piston and cylinder assembly

and the pump body. Confirm the coned end of the seat

is facing up and the cylindrical end of it is facing down.

Thread the high pressure piston and cylinder assembly

(79) or (67) into the outer body outlet as shown, using the

wrenches provided.

Operate the pump handle a few more times until fluid

is observed at the end of the offset pipe. Connect the

gauge or other device to be tested to the offset pipe.

For purposes of priming, the device must be designed

to withstand the full operating pressure of 10,000 psi

(70,000kPa). If a lower range device must be used, ex-

treme care must be exercised to avoid overpressuring

its pressure element. Seal the connection to the device

by tightening nut adapter (62) and adapter (60) until the

coned end of the pipe is forced into its inlet. If necessary,

rotate the device for viewing by loosening nut adapter (62),

set it to the proper position and retighten nut adapter.

Again, operate the pump handle a few more times. After

a few strokes positive pressure will develop and the pump

handle will begin to resist pumping action. Raise the pump

handle to its uppermost travel position. Loosen the bleed

screw (30) a half turn counter clockwise and slowly op-

erate the pump handle through a downward stroke until

fluid flows steadily from the bleed vent. Close the bleed

screw just prior to completing the downward handle mo-

tion. Repeat this action until no air bubbles are observed

in the fluid flow. (Note – the bleed screw must be closed

when the handle is being raised). Push the shuttle valve

in towards the pump body and continue pumping to the

desired test pressure. Open the release valve (37) to vent

the pressure. To check operation pull the shuttle valve

outward, close the release valve and operate the pump

handle several times. When handle resistance is felt, push

the shuttle valve inward and continue pumping within the

range of the test device.

Entrapped air will prevent the pump from operating in the

high pressure valve position or cause it to achieve only

partial pressure. Repeat the above bleed procedure as

necessary to assure all air is removed. Once air is re-

moved the pump will continue to operate without further

attention providing the reservoir level is maintained.

3.3.3 Weights

The weight set consists of a selection of various masses

that will produce desired pressure increments when op-

erated with the appropriate piston and cylinder assembly.

Each weight is stamped with two pressure values. When

applied to the high pressure piston and cylinder assembly

the equivalent pressure value is indicated next to the letter

"H". Conversely, when applied to the low pressure piston

and cylinder assembly the equivalent pressure value is in-

dicated next to the letter "L". The piston and piston platform

also contribute to the total mass. Their equivalent pressure

value is stamped on the top of the platform.

During normal operation, selected weights are added to

the plate and piston assembly to equal the desired pres-

sure value.

3.3.4 Levelness

The deadweight tester must be level to function properly.

The unit may be leveled by placing a bubble type level on

top of the piston plate and revolving it slowly. Shims may

be used between drip pan and bench to level the piston

plate. The unit is level when the position of the bubble

does not change within the glass as it is rotated on top of

the piston assembly.

3.3.5 Making the Test

Add weight to the piston plate to give desired calibrating

pressure.

Pull the shuttle valve (51) outward from the body and

close the pressure release valve (37). Operate the pump

handle until the fluid pressure forces the piston to raise the

weights. When pumping, the weights should be rotated

slowly to decrease cylinder wall friction. If pump handle

resistance is difficult and the weights have not risen, push

the shuttle valve inward and continue pumping. With the

shuttle valve pushed in, the fluid displacement of each

stroke is reduced, thereby requiring less effort to continue

pumping.

The piston assembly has a maximum lift of

cm). It is recommended that readings be taken at mid-

point, or

⁄

inch (1 cm) lift. Small adjustments to the piston

lift can be made with the pump handle or the displacement

valve (41).

Improper readings will result if the piston plate is so low

that it rests on the bushing, or so high that the internal

stop on the piston assembly is touching the underside of

the bushing.

Spin the weights by hand and take readings only when

the weights are spinning. Speed of rotation is unim-

portant, although a slow speed is more convenient and

recommended.

To release pressure, turn valve (37) counterclockwise slowly.

3.3.6 To Dismantle

of 20

⁄

inch (1.9