| 摘要 |
<p>The valve body consists of two blocks (1,2) with side-plates. The blocks are pierced by vertical channels(7,8) connected to four connection pipes (11,12). Within the cavity of the valve body a piston (13) can move horizontally between two limiting blocks. The piston is pierced by three parallel channels (16), and can be moved by a rod when acted on by a membrane in an operating device. In the normal state, the gas which is to be sampled and tested flows through the block without affecting the supply to the chromatograph column. When a sample is required, the piston is retracted by the membrane, carrying a small but measured amount of gas in the piston capillary to the pressurised feed (11, 7, 8, 12) of the column. The flow path for the fluid through the piston is replaced by another capillary through the piston.</p> |
