BLACKMER SNP1.25, Installation, Operation And Maintenance Instructions

104-A00    Page 11/16 

MAINTENANCE 

PUMP ASSEMBLY 

Before reassembling the pump, inspect all component 
parts for wear or damage, and replace as required. Wash 
out the bearing/seal recess of the head and remove any 
burrs or nicks from the rotor and shaft. 

1.  Place a small amount of Moly-grease on all capscrews 

before assembly to prevent galling. 

2.  Start with the OUTBOARD side of the pump. 

Figure 8 – Hole in Disc 

3.  Place the outboard disc (71) and seal ring (72) on the 

cylinder (12) so that the hole in the disc will be toward 
the INTAKE side of the pump. See Fig. 8. 

4.  Place the outboard head (23) on the cylinder (12) with 

the suction groove toward the bottom, using the dowel 
pin (25A) for alignment. See Figure 8.  

a.  Model SNPJ2.5: Place the O-rings (72A and 72B) 

and the steam jacket (59) on the head. 

b.  All Models: Tighten the head capscrews evenly to 

ensure that the head is properly seated and the seal 
ring fully compressed. 

c. 

Secure the bearing cover (27) and seal ring (26) to 
the head with the four capscrews (28). 

Figure 9 – Pushrod Installation 

5.  Rotor and Shaft 

a.  Install the pushrods and the 2 (or 3) bottom vanes 

into the rotor. The rounded edge of the vanes must 
be ouward to contact the bore of the cylinder and 
the relief grooves facing in the direction of rotation.  
See Figs. 5 and 9 

b.  Holding the vanes in place, install the rotor/shaft into 

the cylinder using care not to damage the disc or 
shaft. 

c. 

Turn the shaft by hand until an empty slot comes to 
the 12 o’clock position, insert a vane, and move on 
to the next slot. 

6.  Place the inboard disc (71) and seal ring (72) on the 

cylinder (12) so that the hole in the disc will be toward 
the INTAKE side of the pump. See Fig. 8. 

7.  Place the inboard head over the shaft and against the 

cylinder (12) with the suction groove toward the bottom, 
using the dowel pin (25A) for alignment. See Figure 8. 

a.  Jacketed Models: Place the O-rings (72A and 72B) 

on the head. 

b.  All models except the SNP3A: Place the Bracket / 

Jacket (108 or 59) onto the head. 

c. 

All models: Tighten the head capscrews evenly to 
ensure that the head is properly seated and the seal 
ring fully compressed. 

Figure 10 - Packing 

8. 

PACKING AND PACKING FOLLOWER

When necessary to repack, use a full set of new packing 
rings. Packing is furnished in sets with the correct number of 
rings. Never add new rings to an old set of packing. 

a.  Insert the packing washer (58) into the stuffing box 

of the 

inboard hub.

b.  Insert each packing ring (19) separately into the 

stuffing box, using the packing follower (75) to 
properly seat each ring after placement. Be sure to 
stagger the split joints approximately 180 degrees 
apart so that they are not overlapping or near the 
joint of the preceding ring. 

c. 

Install and tighten the two packing follower studs 
(17). 

d.  Place the packing follower (75) snugly against the 

packing. Install the two packing follower stud nuts 
(18) and 

tighten lightly.  NOTE: 

Adjustment to the 

packing follower should be made while pumping 
liquid (see "Packing Adjustment").