Raising the Pump Risk/Reward
Improving the change out time of the impeller and diffuser is a core need and design specification of the
project. Currently, hex socket bolts are used to seal the housing. These are removed and attached by
using an Alan wrench. Because there is no clearance between the bottom of the housing and the base
plate it rests on, the 2 bolts on the bottom edge of the pump housing have no room for attachment and
removal. There is a maximum 180o range of motion with one bolt, and about 100o on the other bolt.
In addition to tool clearance, the housing does not seal correctly. Since there is no room around the
bottom edge of the pump housing to ensure a proper fit, leaks can form there.
When the pump system is stopped, water either runs out of the discharge or inlet pipes, except for the
fluid still inside the pump housing. This is the system “low point”, and the only way out for the water is
through the bottom of the housing. Since quick and convenient change outs of impellers and diffusers
in a laboratory setting are a project need, more options for system drainage are needed.
The solution to all three of these problems lies in raising the elevation of the pump housing, bearings,
and motor above the level of the base plate. The only question is: How far should the pump be raised?
There are some constraints to the pump housing height.

The “maximum” is determined by a minimum eye clearance for safety when using the PIV laser
with the pump.
o
Because of this eye clearance standard, the top of the pump housing can be no higher
than 48 inches above the floor.

It needs to be ensured that there is sufficient tool clearance for the ¼ - 20 hex bolts by ASME
standards (Ammar’s work here).

The cart on which the pump system rests has a 2 inch lip around the edge that impedes line of
sight of the lower half of the pump housing.

The current system’s inlet pipe needs to be repositioned to accommodate new pump housing
elevation. Discharge is through a flexible tube so it is unaffected.
A basic screen of a few different options on repositioning were explored.
P09454 Pump and Motor Reposition
Selection Criteria
Tool clearance
Material Needed
LOS for PIV
Drainage
Eye clearance (Safety)
LOS for high-speed camera
Sum + 's
Sum 0's
Sum -'s
Net Score
Rank
Continue?
No
Concepts
A
B
C
3 inches
+
+
+
3
0
3
0
3
2 inches
+
+
+
+
0
4
2
1
3
1
1 inch
0
0
0
+
0
1
5
1
0
3
Yes
No
D
(Reference)
0 inches
+
+
+
3
0
3
0
3
No
Table 1: Pump Reposition Screen
Though the 2 inch option looked most attractive, it needed to be proven.
With a 2 inch rise, and adding in a 10 inch square pump housing, the new system maximum height is
46.75 inches, within the laser eye clearance. This height is the minimum required to place the entire
pump housing above the steel lip currently obstructing line of sight of the flow. Additionally, the inlet
pipe can be repositioned to feed into the elevated housing with virtually no system redesign, something
that the 3 inch reposition cannot offer.
All in all, a repositioning of 2 inches offers the most relevant benefits to the projects specifications, while
not conflicting with any customer needs.