MIL-HDBK-1003/11
available compressed air. However under emergency conditions, the manifold
allows for alternate supply from other tanks to the engines.
c) Starting air pressure shall be as recommended by the engine
manufacturer. Normal starting air pressure is 250 lb/in2 (17.5 kg/cm2),
with a 300 lb/in2 (21.0 kg/cm2) design pressure.
d) Receiver construction shall conform to American Society of
Mechanical Engineers (ASME) SEC 8D, Pressure Vessels, for the system
pressures involved.
5.4.12.4 Electric Starting. In standby/emergency duty plants serving
emergency loads and where compressed air will normally not be provided,
electric starting using batteries may be employed if standard with the
engine manufacturer. Electric starting batteries shall be furnished to
provide the same starting capacity as is required for air starting receiver
capacity. Batteries shall be heavy duty type complete with battery racks,
cabling, chargers, meters, hydrometers and controls as recommended by the
engine starter and battery manufacturers.
5.4.12.5 Preheat System for Testing Standby/Emergency Duty Units.
Consider
providing engine coolant and lubricating oil preheating systems to
facilitate scheduled tests of generator sets.
5.4.13 Foundations. Diesel engine-generator unit foundation design must
take into account the dynamic characteristics of the soil (refer to NAVFAC
DM-7.01, Soil Mechanics) and machinery characteristics to avoid resonance of
the foundation with the operating equipment. Investigation of these
characteristics often results in inexact data and thus requires field
adjustments to the design. The design guidelines given herein should be
considered minimums to be adjusted to meet actual requirements. Consult
NAVFAC DM 7.02, Foundations and Earth Structures, for further discussion of
vibration problems and examples of design to avoid resonance and for shock
and vibration isolation.
5.4.13.1 Investigation. The following investigations are necessary for
units larger than 750 kW, and elsewhere, where special conditions indicate
such a need:
a) Soil Characteristics. Dynamic properties vary widely and can
be defined only roughly within rather wide limits. Each type of soil, sand,
gravel, clay, rock, and the degree of moisture saturation of the soil
provides a different and widely varying response to dynamic loads. Size of
bearing area and its dimensions may also influence dynamic properties of the
soil.
b) Machinery Characteristics. The equipment manufacturer usually
provides estimated values based on equipment dimensions, eights, and
operating speeds which may not furnish precise values. Beyond the usual
static data, it is necessary to have such data as the unbalanced forces and
couples with their location, magnitude, and direction (both primary and
secondary); plus starting torque and stopping torque, without load and with
full load on the generator.
5.4.13.2
Design.
As a design basis, a designer uses data regarding soil
and
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