MIL-P-19692E
3.3.12 Pressure pulsations. Pressure pulsations are the oscillations of
the discharge pressure, occuring during nominally steady operating
conditions, at a frequency equal to or higher than the pump drive shaft speed.
The amplitude of pressure pulsations shall be determined by the test procedure
of 4.3.2.1.6.4. These pulsations shall not exceed ± 300 psi (± 2100 kPa) under
any condition, or a pressure band specified by the detail pump specification.
The pump shall be tested in the circuit which simulates the actual system in
which the pump is to be installed, as defined in the detail pump specifica-
tion. The system volume shall be simulated using tubing of the discharge line
diameter. A tubing line length whose natural frequency is resonant with
pulsation frequency shall be avoided.
3.3.13 Variable flow control. The pump shall incorporate flow control
means which shall act to increase the flow of the pump from zero to its
maximum full-flow value for any given operating speed as the discharge
pressure is reduced from rated discharge pressure to maximum full-flow
pressure and vice versa.
3.3.13.1 Response time. The response time of the pump shall be the time
interval between the instant when an increase (or decrease) in discharge
pressure change initiates; and the subsequent instant when the discharge
pressure reaches its first maximum (or minimum) value. In figures 3 and 4,
the time intervals T1 and T2 are the response times of the pump as a function
of the system impedance. The oscillographic trace of discharge pressure versus
time shall be employed as the criterion of movement of the flow control
mechanism. All pump models when operating at rated inlet temperature at rated
speed and in a circuit whose system impedance as specified in 4.3.2.1.6.1.1
for response tests, shall have a response time of .050 seconds maximum unless
otherwise specified in the detail pump specification.
3.3.13.2 Stability. The stability of the pump shall be the freedom from
persistent or quasi/persistent oscillation or "hunting" of the flow control
mechanism at any frequency that can be traced to the pump flow control means.
The oscillographic trace of discharge pressure versus time shall be employed
as the criterion of the stability. All pump models, under any operating
condition within the limits established in the detail pump specification and
at any speed greater than 50 percent of rated speed, after being disturbed
from steady-state operation by a change in flow demand or a change in pump
speed, shall recover steady-state operation (other than permissible pressure
pulsations as specified in 3.3.12), within one second after initial response
to that change in flow demand. When required by the contracting activity, the
pump manufacturer shall provide pump data to permit the system designer to
integrate pump dynamic performance into his complete pump and system analysis.
3.3.13.3 Maximum transient pressure. The maximum transient pressure
shall be the peak value of the oscillographic trace of discharge pressure,
made during operation of a pump, as specified in 4.3.2.1.6.2 and measured as
shown on figure 3. The maximum transient pressure, as determined in the
transient pressure test specified in 4.3.2.1.6.2, shall not exceed 135 percent
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