Machine reach point

Design The economics usually work out in the favor of gas coolers when the centrifugal machines flow rate reaches about 5000 scfm. The pressure loss can Be kept to 7.0 kPa in most cases. When the ratio of A(ht lo Ajhs is 20 1, is another point to consider these plate-fin designs. Vibration is practically impossible with this design, and uses in reciprocating compressors are possible due to this. 

As an example of using a Mollier diagram in defining the state of air, we can take a typical measurement from the local exhaust hood of a paper machine. Tbe temperature of the exhaust air is 82 C and its wet bulb temperature 60 "C. In Fig. 4AQd we move from the saturation curve at the point 60 °C straight up along the constant enthalpy line ( = 460 kj/kg d.a.) until we reach the isotherm... 

Low-limit alert The first alert (i.e., low-limit alerta) should be set at the lowest vibration amplitude that will be encountered from a normally operating machine-train. This value is needed to ensure that valid data are taken with the microprocessor. If this minimum amplitude is not reached, the system alerts the operator, who can retake or verify the data point. Low-limit selection is arbitrary, but should be set slightly above the noise floor of the specific microprocessor used to acquire data. 

A side benefit of predictive maintenance is the automatic ability to monitor the mean-time-between-failures, MTBF. This data provides the means to determine the most cost-effective time to replace machinery rather than continue to absorb high maintenance costs. The MTBF of plant equipment is reduced each time a major repair or rebuild occurs. Predictive maintenance will automatically display the reduction of MTBF over the life of the machine. When the MTBF reaches the point that continued operation and maintenance costs exceed replacement cost, the machine should be replaced. 

Example 62 If a manufacturing process involves two raw materials, each defined by three sets of specification limits, and four pieces of equipment with one control knob, then a complete validation protocol would ask for (Three settings Lo, Target, Hi) (2 materials 3 specs + 4 machines 1 control) = 3 = 59 000 experiments, even without repetitions. This product would never reach the market if one did not employ experience and scientific rationale to simplify development by testing only the presumed critical issues, say a total of three specification points for 3 = 27 experiments. 

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