TABLE FOR GUIDENCE TO THE SELECTION OF A SUITABLE VACUUM PUMP FOR DEGASSING. (Rate of Evacuation for Various Cylindrical Vacuum Chambers)
| Dimensions of vacuum chamber (in mm) |
Gross volume of vacuum chamber (in litres) |
Max holding capacity of RTV silicone rubber based on X6 expansion (in grams) |
Speed of vacuum pump required (in CMH) to reach a vacuum of 10 Millibar in time shown below |
| Diameter & height |
|
|
5 mins |
3 mins |
2 mins |
1
min |
30 sec |
175 x 175 |
4.2 |
600 |
1.0 |
1.0 |
1.0 |
2.0 |
3.0 |
230 x 230 |
9.6 |
1400 |
1.0 |
1.0 |
2.0 |
3.0 |
6.0 |
305 x 150 |
11.0 |
1600 |
1.0 |
1.5 |
2.0 |
4.0 |
7.0 |
305 x 230 |
16.0 |
2300 |
1.0 |
2.0 |
3.0 |
5.0 |
10.0 |
305 x 305 |
21.0 |
3000 |
2.0 |
3.0 |
4.0 |
6.0 |
13.0 |
305 x 460 |
32.0 |
4700 |
2.0 |
4.0 |
6.0 |
10.0 |
20.0 |
380 x 330 |
37.0 |
5400 |
3.0 |
4.0 |
6.0 |
11.0 |
22.0 |
460 x 150 |
34.0 |
3500 |
2.0 |
3.0 |
4.0 |
7.0 |
13.0 |
460 x 230 |
37.0 |
5400 |
3.0 |
4.0 |
6.0 |
11.0 |
22.0 |
460 x 305 |
48.0 |
7000 |
3.0 |
4.0 |
9.0 |
15.0 |
30.0 |
460 x 460 |
72.0 |
10500 |
6.0 |
9.0 |
12.0 |
22.0 |
44.0 |
460 x 610 |
95.0 |
14000 |
6.0 |
10.0 |
15.0 |
30.0 |
65.0 |
500 x 500 |
100.0 |
14600 |
6.0 |
10.0 |
15.0 |
33.0 |
65.0 |
500 x 760 |
152.0 |
22000 |
9.0 |
15.0 |
23.0 |
44.0 |
90.0 |
610 x 460 |
127.0 |
18600 |
8.0 |
12.0 |
20.0 |
40.0 |
74.0 |
760 x 305 |
136.0 |
19000 |
8.0 |
14.0 |
22.0 |
45.0 |
88.0 | All dimensions and rates are approximate Recommend maximum pump down times: RTV Silicone rubber and most resins: 3 minutes. Casting and Investing Plasters: 1 minute. Polyurethane: 30 seconds. Please refer to material manufacturers specifications, which should give the pot life of the material | 
