It's common practice in the oil and gas industry to inject a drive gas or fluid into a well and then release it into the atmosphere once it has done its job.
But the industry is being required to recover these fluids and gases. To do so, engineers at Morrison Machine Works, Fort St. John, British Columbia, developed a four-way valve that controls two gas or fluid streams at once.
The requirements were daunting. The valve had to be mechanically activated because there is rarely electrical power at well sites. So it had to rely on existing pressure drops (differentials). The valve had to be bistable and could not let pressure equalize throughout the system. It would also have to be simple to operate and maintain, and provide a year of continuous service (5 million cycles).
The engineering team finally decided on using a bistable Clover disc spring from Schwab-Koplin Assoc., Port St. Lucie, Fla., to position the fourway valve's shuttle. A patented system of radial and axial seals allows low shuttle/spool shifting forces while maintaining a tight seal necessary to avoid pressure equalization. The design uses only three moving parts. The finished valve injects chemicals into a 1,200-psi pipeline using 5 psi of existing pressure drop and an intensification system.