Type P.B./S.T.
This Rotary (P.B.) Union is fitted with an elbow suitable for double flow with a stationary centre tube. This gives flow areas through the centre tube and annulus. Centre tubes are only provided if ordered. The centre tube is fixed to the Rotary (P.B.) Union end by means of a screw thread shown as dimension “O”. Flow can pass in through the centre tube and return through the annulus or be reversed.
For steam applications the centre tube is curved to reach the condensate in the bottom of the cylinder. At times the roll neck diameter to length ratio prevents a curved tube being used, in such cases we can provide a Syphon Elbow.
Type P.B./S.T. for double flow stationary centre tube
| Nominal size |
A | Part No. |
| 15 (½”) | G.½” | 18467 – R or L |
| ¾”-16 UNF | 18467U – R or L | |
| M22 x 1.5 | 18467MB – R or L | |
| 20 (¾”) | G.¾” | 18470 – R or L |
| 1″-14 UNS | 18470U – R or L | |
| M30 x 1.5 | 18470MB – R or L | |
| 25 (1″) | G.1″ | 18473 – R or L |
| 1½”-12 UNF | 18473U – R or L | |
| M35 x 1.5 | 18473MB – R or L | |
| R, L depend on the direction of rotation | ||
| Nominal size |
B | C | D | E | F | G | H | I | J | K | M | O | Q | U | V |
| 15 (½”) | G.½” | 13 | 193 | 130 | 29 | 16 | 44 | 68 | 181 | G.¼” | 30 | G.1/8″ | 12 | 173 | 38 |
| 20 (¾”) | G.¾” | 18 | 196 | 133 | 32 | 19 | 44 | 68 | 184 | G.¼” | 30 | G.¼” | 12 | 176 | 38 |
| 25 (1″) | G.1″ | 22 | 210 | 148 | 43 | 22 | 52 | 88 | 197 | G.3/8″ | 25 | G.3/8″ | 9.5 | 185 | 42 |
| Dimensions in millimetres | |||||||||||||||
‘G’ is the designation for parallel pipe threads to BS2779 and ISO 228/1
