YAMADA DP-20F/P, Maintenance Manual

Page: 9 / 16

6
<NOTE>
▪ Make sure the sealing surface is not dirty or damaged.
▪ Tighten the nuts evenly and alternately in a diagonal
sequence to the specified torque.
▪ Make sure that the directions of each coned disk spring
are correct. [Fig.4.11]
▪ Attach the pilot valve and bushing securely.
(See [5.3 Installation])
▪ Retighten the tie rods before starting the pump.
(See [7. Retightening of tie rods])
5. Pilot Valves Assembly, Valve Seats
5.1 Removal
▪ Remove the diaphragms and center rod.
(See [4.1 Removal]).
▪ Remove the valve seats from the body assembly using the
pilot valve remover (special tool: Part No. 712606).
▪ Remove the O rings, pilot valve assembly, and springs.
[Fig.5.1]
5.2 Inspection
▪ Pilot valve assembly [Fig.5.2]
Measure the diameter, and if it is not within the permissible
range, replace the pilot valve assembly with a new one.
Permissible range of diameter of pilot valve
DP-20F/P Ø 4.8 - Ø 5.0 mm
DP-25F/P, DP-25F/C,DP-38F/P, DP-38F/C Ø 6.7 - Ø 7.2 mm
▪ Valve seat [Fig.5.3]
Measure the inside diameter, and if it is not within the
permissible range, replace the valve seat with a new one.
Permissible range of valve seat diameter
DP-20F/P Ø 7.0 - Ø 7.2 mm
DP-25F/P, DP-25F/C,DP-38F/P, DP-38F/C Ø 10.0 - Ø 10.2 mm
▪ Spring
Always replace the springs at the time of maintenance.
▪ O ring
Replace the O ring if it is worn out or damaged.
Fig.4.11
Fig.5.1
Fig.5.3
Fig.5.2
DP-20F/P, DP-25F/P
Fig.4.10