SUBJECT: Your rejection letter of 21 June 1977 and disapproval of the factory test data, transmitted in Transmittal #12

Dear Colonel Chandler,

The purpose of this letter is to register our protest regarding your rejection of the subject pumps. Our protest is based on the following considerations.

We do not agree that the submitted factory data indicated unstable pump performance near the priming point. We are aware that instability is a characteristic of some high specific speed pumps operating at high heads; however, this characteristic is manifested by (a) a pronounced dip on the H-Q curve and (b) noisy pump operation, neither of which were recorded during the factory test. Your attention is invited to figure (1) attached, which shows the results of preliminary factory tests on the North Pump with different impellers. Note the pronounced dip in the H-Q curve for the 48° impeller at approximately 34-1/2 feet of head. This, along with the fact that the pump was noisy in that region, indicated unstable operation. We rejected that particular impeller for that reason. By comparing the H-Q curve on figure (1) with that submitted, it is evident that the North pump as currently configured is stable over its entire range of operation.

In addition, your reference to the sump model test data and the inference that it in any way verifies the factory test results is grossly unfair for the following reasons.

As stated in the approved test plan, the purpose of the pump model tests was to prove the subject pumps' performance under minimum submergence conditions, and not to verify the factory test results.

1

As it turned out, the results were inconclusive for several reasons, among which were:

(a) At your request the test was expedited so, the contractor's installation schedule could be met. As a result we did not have adequate time to prepare the test facility to obtain viable data under high head conditions.

(b) The zero reference on the hook gauge was inadvertantly moved during the test.

(c) Motor speed measurements were not taken.

(d) The head gauge had not been calibrated in the higher head range.

For these reasons a report was neither prepared nor submitted for your consideration at that time. However, copies of the raw (uncorrected) test data were provided as a courtesy to your representatives, for their information only.

In view of those June 3, 1977 test results, we modified our test procedure and re-scheduled the test for June 16, 1977. While the results of the latter tests were more encouraging, we were still not satisfied with them because the repeatability of the data points at the high head end of the curve was very poor. For this reason, we again elected not to submit a report and again, we provided courtesy copies of the raw test data to your representatives.

After the above experience, we are convinced that the probler is not with the pumps nor with the test procedure, but with the test facility itself. Basically, this facility was designed to examine pump performance under low head, high flow conditions as these are the conditions that are most conducive to cavitation and vortexing problems; however, it is obvious that in the case of the subject pumps, the emphasis has shifted to the opposite end of the curve: To the high head, low flow condition, and that our test facility is inadequate to provide reliable data in that area. Therefore, we are presently modifying our test facility with the hope that such modifications will enable us to obtain meaningful data on the subject pumps performance under the aforementioned conditions. These modifications include:

(a) Relocation of the throttling valve.

(b) Modification of the baffles in the flume to reduce the turbulence.

(c) Installed

36" Mercury manometer to measure head per the

Hydraulic Institute Standards:

5B

RE: Factory Tests

Modifications (cont.)

(d) Purchased an electronic tachometer.

(e) Relocated the pressure tap to the discharge ell, so that we can read field pressure directly. Velocity head will be calculated at that point, per the Hydraulic Institute Standards also.

As stated in Section 3 of Applicable Contract Specification, we are obligated to provide you with a low submergence test report on the subject pumps. It is our intention to fulfill that obligation and we are currently working toward that end. Therefore, we respectfully request your indulgence in holding any decision regarding the acceptance or rejection of the subject pumps until we have had a chance to complete the low submergence test and submit the results to you, per your specification..

Respectfully,

HYDRONIX, INC.

Floyd A. Chapman/ms

encl

SUBJECT: NORTH PUMP STATION PROTOTYPE PUMP

BID ITEM 0002 - PRELIMINARY MINIMUM SUBMERGENCE
TEST REPORT

PROJECT: SCAPPOOSE DRAINAGE DISTRICT

NORTH PUMP STATION

CONTRACT NO. DACW57-75-C-0195

REF: (a) Specification Section 3 thru 3-4.2

TESTS

(b) Hydraulic Institute Standards, 12th Edition 1969.

1. INTRODUCTION

a. The subject preliminary report is submitted in compliance
with reference (a).

b. The purpose of this test was to determine the prototype pumps' performance under the minimum submergence condition.

c. Background

(1) The subject pump was initially tested at the manufacturer's
facility on 22 March. 1977. The purpose of that test was
to verify that the pump's performance met the contract
specifications. The effects of minimum submergence were
not investigated: at that time. That test was witnessed
by a U.S. Army Corps of Engineers representative, and
the results reported separately.

(2) Preliminary tesis on the subject pump were conducted at the Hydronix, Inc. facility where the effects of minimum submergence on pump performance (vortexing and cavitation) were investigated. Those particular tests were held on 3 June and 16 June 1977. While no vortexing

RE: Test Reports

6A

or cavitation was observed at that time, intermittant unstability was noted when the pump was operating at its' priming point. In addition, the repeatability of the test data was poor wher. operating at the high head end of the curve. Since those observations were contrary to those observed during the factory tests, it was concluded that the Hydronix, Inc. test facility, as configured at that time, was inadequate to provide viable results under high head conditions. For this reason the facility was revised and the preliminary tests repeated on 5 July 1977. The results of those tests are the subject of this report.

a. The subject pump was visually inspected to assure it was in satisfactory mechanical condition.

b. The prototype pump was assembled with the suction umbrella, discharge head, head shaft and motor. It was then mounted on the test rack. See figure (1). Pump rotation was checked and the impeller bowl clearance adjusted, per the manufacturer's instructions.

The pump submergence was adjusted to 2.1 feet with the pump running. The clearance between the suction bell lip and the sump floor then adjusted to 0.67 feet. See figure (2).

d. A pressure tap was installed at the discharge end of the pump elbow and connected to a mercury manometer as shown in figure 41 in reference (b).