Model 988-MB
SKU#:
Model 988-MB
Description
The Cashco Model 988-MB is a variation of the basic Cashco Model 988 globe-style control valve that incorporates a metallic bellows stem seal. The purpose of the design is to maximize the reduction of fugitive emissions of hazardous fluids in the chemical industry from one of the most common sources – conventional control valve stem packing.
The bellows is designed conservatively, in that there are a relatively large number of convolutions to keep bellows internal stresses to the lowest practical levels, optimizing expected cycle life, and minimizing effects of bellows “snaking”.
Design Pressure
Maximum Allowable Working Pressure: Up To 200 psig (13.8 Barg)
Line Sizes
- 3/4" (DN20)
- 1" (DN25)
- 1-1/2" (DN40)
- 2" (DN50)
End Connections
- NPT
- FLANGED
- SOCKET WELD
Body Materials
- Stainless Steel
- Carbon Steel
Features
- Designed for providing long service life where environmental and personnel protection are of primary importance.
- 70K–250K average stroke cycle life at 200 psig and 200°F (13.8 Barg and 94°C).
- External pressure loading to reduce “snaking” and optimize location of convolution stresses.
- Anti-rotation stop to prevent undesired bellows rotational forces.
- Sufficient number of convolutions to provide full design stroke.
- Live-loaded secondary stem packing seal.
- Leak-off connection with slotted plug; for use in alerting of bellows leakage.
- Designed with bellows “neutral zone” at optimum position for longest life.
- Two bellows materials – 316L and Hastelloy C – to cover majority of corrosive fluids.
| Line Size | 3/4" (DN20), 1" (DN25), 1.5" (DN40), 2" (DN50) |
|---|---|
| End Connections | FNPT, Flanged, Socket Weld |
| Service | Gases, Liquids |
| Body Material | Carbon Steel, Stainless Steel |
