Troubleshooting guide

15
72-001-02 Rev A
6.3 Check Valves
Most fluid metering service requirements are related to check valves. Service requirements usually stem
from solids accumulation between valve and seat, corrosion of seating surfaces, erosion, or physical
damage due to wear or the presence of foreign objects.
The valve incorporates a ball, guide, and seat. Flow in the unchecked direction lifts the ball off the seat,
allowing liquid to pass through the guide. Reverse flow forces the ball down, sealing it against the sharp
edge of the seat. The guide permits the ball to rotate but restricts vertical and lateral movement in order
to minimize “slip” or reverse flow. Ball rotation prolongs life by distributing wear over the entire surface
of the ball. Since ball return is by gravity, the valve must be in the vertical position in order to function
properly. Parts are sealed by “O”-rings.
All BLACKLINE models utilize a convenient cartridge-type check valve. All check components are pre-
assembled and the cartridge should be replaced as a unit. When replacing, note that valves are marked
with the flow direction, as the suction and discharge configurations are different.
Figure 9, check valves
Figure 8, check valves to 60 GPH