4
5. Threaded Valves
The disassembly of all valves follows the same basic procedure. This
section pertains to 2700, 2850, 2856, 1890, and 1896M Series Valves.
Please refer to the appropriate drawings.
1. Place the valve at a suitable height. The work surface should be clean
and strong enough to handle the weight of the parts and the forces
required during disassembly and assembly.
2. Mount valve vertically in a vise using the flats on the body.
3. Remove all wire seals from external adjustments.
4. Unscrew the cap by turning counterclockwise. Remove the cap gasket.
For valves with open or packed lever assemblies, see Section 6.
5. Measure the distance from the top of the spring adjusting screw to the
top of the bonnet. Use this measurement when reassembling the valve
to approximately duplicate the original set pressure.
6. Using a smooth jaw wrench, hold the spring adjusting screw and
remove the spring adjusting screw jam nut.
7. While holding the stem with a smooth jaw pliers, remove the spring
adjusting screw by turning counterclockwise.
8. On 2850 & 2856 Series, remove the blow down ring lock screw
and gasket.
9. Thread a pipe into the outlet and turn the bonnet counterclockwise,
removing it from the body.
10. Remove the stem with spring and buttons attached. On Series 2850
and 2856 valves, the upper and lower spring buttons are different.
11. Remove the spring and buttons from the stem.
12. On the 2850 and 2856 Series, the disc is held to the stem with a pin.
The disc will come off when the pin is removed.
13. 2700 Series Only: Remove the body from the vise and invert assembly,
carefully removing the guide which contains the disc and disc holder.
The disc and disc holder may now be removed from the guide.
2850 & 2856 Series Only: Unscrew the blow down ring from the body.
1890 & 1896M Only: Remove the lift stop ring from the guide. Remove
the body from the vise and carefully invert it, allowing the disc to fall
free. Unscrew the guide from the body.
14. Proceed to Section 7 for instructions on cleaning and lapping.
15. Reassemble valve in reverse order making sure that lapped body and
disc seating surfaces are not damaged. All threaded connections
should be properly coated with an appropriate lubricant.
16. Proceed to Section 8 for testing procedures.
Figure 2: Series 1890 & 1896M
