ASME PTC-2:2001 pdf free download

ASME PTC-2:2001 pdf free download.DEFINITIONS AND VALUES.
2.1 INTRODUCTION
The Codes provide test procedures which yield results of the highest level of accuracy consistent with the best engineering knowledge and practice. taking into account the cost of tests and monetary value of efficiency to industry. Performance of equipment is determined in )rt by measurements of physical quantities. A measurement consists of sensing a physical variable and translating this result into data that is either indicated or recorded. Analog data are indicated by the position of a pointer on a dial or by a point or line on a chart. Digital data are indicated by a visual display of numbers or by a numerical printout. Devices used to make measurements are called instruments but many devices called instruments must be used with additional components to measure certain physical variables and quantities. A millivoitmeter, for example, can measure voltage but a thermocouple must be used in conjunction with the voltmeter to obtain a temperature measurement.
2.2 MEASUREMENT SYSTEM
In order to make a measurement of a physical quantity it must first be sensed, and the information about the energy change due to sensing must be transmitted to a component that communicates the data. The requirements for measurement are met by the system shown in Fig. 2.2.
The primary element is that part of the measurement system that first senses the variable to be measured. The energy change produced by the sensing must be transmitted to an inlormation-communicating unit where it may be used directly or changed (transduced) to some other form to indicate or record data. The measurement system may be very simple or very complex but the three functions appearing in Fig. 2.2 are required to make a physical measurement. The measurement system may be a single component such as a liquid-in-glass thermometer
Water vapor is one of the products of combustion for all fuels which contain hydrogen. The lower or higher heating value of a fuel depends on whether this water vapor is allowed to remain in the vapor state or is condensed to liquid. In a bomb calorimeter, the products of combustion are cooled to the initial temperature and all of the water vapor formed during combustion is condensed to liquid. This gives the higher, or gross, heating value of the fuel with the heat of vaporization included in the reported value. For the lower, or net heating value, it is assumed that all products of combustion remain in the gaseous state.
While the higher, or gross, heating value can be accurately determined by established ASTM) procedures, direct determination of the lower heating value is difficult. Therefore, it is usually calculated.
horsepower: the term was originated by Boulton and Watt to state the power of their steam engines. In a practical test, it was found that the average horse could work constantly at a rate of 22,000 litlb)/min. This was increased arbitrarily by half to define the now universal unit of power: 550 (ftlbVsec.
hydrocarbons: any chemical compounds containing only hydrogen and carbon; these are frequently used as fuels. Physical properties in NIST database IDMIX permits the determination of thermodynamic and transport properties of fluid mixtures of various pure gases and heavy hydrocarbons.
ice point: the temperature of an equilibrium mixture of liquid and frozen pure water melting under one standard atmospheric pressure absolute
(273.15 K).
internal combustion cycles: for internal -combustion engines, several cycles are in common use, e.g., the Otto and Diesel cycles. It is possible to compute an engine efficiency of ideal cycles. For PTC work, all internal-combustion engine thermal efficiencies shall be determined by a measured work output divided by measured heat input. Engine efficiency shall not be calculated as based on any idealized cycle for internal -combustion engines.