3-1

3. OPERATION

This

paragraph describes the method

of operating

the PW

1720

and

the options,

such as timers etc., but does

not

include operating instructions for

accessory

devices

such

as

cameras and

vertical goniometers.

The initial installation of the PW 1720 is described in the Service part of the manual.

3.1.INITIAL CHECKS

Before switching on the generator, check the following:

- Check that HT tank transport fixing screw is removed, see Service installation section.

- Cooling water for the X-ray tube is turned on.

- The tube shield is fixed in the required position ( 0 ° , 4 5 ° , or 90°).

- The X-ray tube installed is suitable for the analysis program.

-The kV and mA controls are in minimum position (10 kV and 5 mA), also refer to paragraph 3.6.

-The PW 1161 X-RAYS ON lamp (if fitted) is correctly wired, and is placed in a conspicuous position.

-The timers (if required) are installed.

- The

accessory

units,

required

for the analysis program, are correctly fitted

to the

tube shield.

The

white

push-button

must be

depressed by the accessory, and the shutter

disc is

rotated to allow the

X-ray

beam

to

pass.

 

 

 

 

- Set the filter disc to the desired position.

- Check that the a.c. mains stabiliser is correctly installed, when required.

3.2.SAMPLE ANALYSIS

The

procedure

for

analysis

will depend on the accessories being

used,

and

the

operation

of

these devices

is

described separately

in the

respective manuals. They should be

made

ready

for

analysis

by

loading the

sample,

film

(etc.), or

positioning

the goniometer or other device -see

also paragraph 3.4.

 

 

 

•Momentarily operate the GENERATOR I push-button, and when the safety circuit is complete the X-RAYS

ON lamp(s) will light to show that X-rays are being generated. The lamp in the push-button is also lit.

• Increase the

kV

control to the

required value,

then adjust the mA control until the desired

X-ray

tube

current is indicated by the

meter. Do not exceed the rated maximum power to the X-ray tube, i.e.

 

the setting of

kV

and mA

must

not exceed the

values shown for

X-ray tubes in Appendix 1.

The

ratings

shown in the “X-ray diffraction tubes” leaflet (9499 300 10311)

are not applicable.

 

 

•Determine the exposure time, and set the timer if fitted - also refer to paragraph 3.3.

•Place the SHUTTERS three - position switch to select the desired window shutter (with timer), or infinite time (middle position).

•Open the shutter by simultaneously pressing the lowest SHUTTERS push-button, and the SHUTTERS I push-button corresponding to the window shutter which is to be opened, refer to figure 3.1. The shutter will remain open until the timer exposure time has elapsed, or until the SHUTTERS 0 push-button is

operated (when a timer is not fitted or used).

 

 

 

 

 

 

 

 

 

 

During the time that the shutter is opened, the X-ray beam

is allowed into the camera or goniometer, the red

lamps

on the tube shield

below the shutter/filter

disc

are lit,

and

the red

flags

will

appear

in the

side holes

of the cover over the tube shield mechanism

In the

event

 

of a

failure

of one

of

the lamp

bulbs

in the

tube

shield, the shutter is

closed immediately.