Varian VHS-250, Инструкция по эксплуатации

Страница: 39 / 60

VHS-4, VHS-6 and VHS-250 Diffusion Pumps
D
R
A
FT 3/9
/
05
3-3
3.4 VHS-4 and VHS-6 Cold Cap Removal/Installation
To remove the cold cap:
1. Remove the spring (1) (Figure 3-1) attached by round head screw (2), a flat washer (3)
and a lock washer (4). The screw types are:
❑
VHS-4: no. 8-32x
3/16
❑
VHS-6: no. 6-32x
3/16
2. Loosen the nut (5) holding the cold cap bracket (6) to the copper bar (A) and remove the
cold cap (7) from the top of the jet cap (8).
3. Unscrew the no. 8-32x
1/4
socket head cap screw (9) from the top of the ceramic standoff
(10).
4. Remove the ceramic standoff (10) and the no. 8-32x
1/2
stud (11).
To install the cold cap:
1. Thread the 8-32 stud (11) into the ceramic bushing (10) until it bottoms (finger tight).
2. Thread the 8-32 hex socket head screw (9) into top of ceramic bushing (10) until it
bottoms.
3. Install the ceramic bushing assembly onto the top of the jet cap (8) by threading stud
(11) into the tapped hole in the top jet cap. Install finger tight.
4. Attach spring clip (1) to cold cap (7) with 6-32 screw (2) and washers (3 and 4) so that
the clip rests on top of sleeve (12).
5. Lower the cold cap assembly carefully onto the top of the jet cap assembly (8). The
ceramic bushing fits in sleeve (12) and the clamp bar (6) straddles the body bar (A).
6. Lower the cold cap until the horizontal portion of the spring clip (1) touches the head of
screw (9). Ensure that the clearance between the cold cap and the top jet cap is even
around the periphery and that the cold cap assembly is level with the pump inlet flange.
7. Carefully tighten the captive bolt (5) ensuring that there is no strain on the ceramic
bushing and no shift in the position of the cold cap.
Figure 3-1 VHS4 and VHS-6 Cold Cap Removal/Installation
1
7
5
6
2, 3, 4
9
10
11
8
A
12