Hale RSD - Manual (Page 18)

❑ Introduction
18 Section 2: Introduction
Hale Products, Inc., Nov. 2005, Rev-A
Clearance Rings
Clearance rings prevent pressurized water that is leaving the pump volute
from returning to the intake of the impeller. Clearance rings at the impeller
intake also prevent leakage, accomplished by limiting the radial clearance
between the spinning impeller and the stationary clearance ring. Also see
Figure 2-3: “Typical Pump and Gearbox Overview” on page 17.
Typically, a clearance ring has a radial clearance of about 0.0075” (0.191
mm) or between 0.015” to 0.020” (0.381-0.508 mm) per side. However, due
to foreign material found in the water, this clearance increases over time
as the pump is operated. Clearance rings are designed for replacement
when wear limits cause the pump to exceed NFPA standards for satisfactory
performance.
Mechanical Seal
The “maintenance-free,” mechanical seal is common to Hale pumps. (See
Figure 2-5: “Typical Mechanical Seal Overview.”)
The stationary
seat is in con-
stant contact with
a rotating seal
ring to prevent
leakage. The
sealing dia-
phragm is made
of a rubber elas-
tomer specifically
designed for
high-tempera-
ture operations.
Note: Mechanical seals do not drip like other pump packing. A Hale pump with a
drip from the seal requires service.
WARNING !
IF A PUMP IS OPERATED WITHOUT WATER FOR EXTENDED PERIODS, OR
WITHOUT DISCHARGING WATER, IT COULD OVERHEAT. THIS CAN DAM-
AGE THE MECHANICAL SEAL OR THE DRIVE MECHANISM.
Figure 2-5: Typical Mechanical Seal Overview