ASME B40.200-2008 pdf download.Thermometers, Direct Reading and Remote Reading.
1 SCOPE This Standard is confined to analog, dial-type bimetal- licactuated thermometersutilizinghelicalbimetallicele- ments that mechanically sense temperature and indicate it by means of a pointer moving over a scale. 2 TERMINOLOGY AND DEFINITIONS accuracy: the conformity of indication to an accepted standard or true value. Accuracy is the difference (error) between the true value and indicated value expressed as a percentage of span. It includes the combined effects ofmethod, observer, apparatus, and environment. Accu- racy error includes hysteresis and repeatability errors but not friction error. accuracy, reference: the accuracy of a thermometer under reference conditions [normal position at 20°C ± 1°C (approximately 68°F ± 2°F) and 29.92 in. Hg (101.32 kPa) barometric pressure]. adjustment, pointer indication: a means of causing a change in indication. The change is approximately equal over the entire scale. Some examples of this type of adjustment are adjustable pointers, rotatable dials, or other similar items. This adjustment, if provided, is gen- erally accessible to the user. bezel: see ring. bimetallic element: see element, bimetallic. bulb: a termsometimes used to describe the temperature- sensitive portion of the stem (see also length, sensitive portion). bushing: a fitting usually provided with external threads for attachment to a vessel. A bushing does not have a pressure-tight sheath below the external threads. calibration: the process of causing the thermometer to indicate within specified accuracy limits. calibration verification: the checking of a thermometer by comparison witha givenstandard to determine the error at specified points on the scale.
case, liquid-filled: see thermometer, liquid-filled. case, sealed: a case that is sealed but need not comply withthe hermetic seal testas prescribed inthis Standard. case size: see size, case. Celsius: SI unit of temperature measurement (formerly Centigrade), abbreviation °C. Centigrade: see Celsius. conditions, environmental: the conditions, other than pro- cess, that are external to the thermometer including weather, temperature, humidity, salt spray, vibration, corrosive atmosphere, etc., and could affect the ther- mometer’s performance or life. connection, adjustable angle: one that allows case rotation of 360 deg and stem adjustment of at least 90 deg (see Fig. 1). connection, back: (90-deg back angle, rear connection) one in which the stem projects from the rear of the case at a 90-deg rear angle to the dial. connection, bottom: (straight form, lower connection) one in which the stem projects downward from the case, parallel to the dial. connection, left-side: one in which the stem projects from the left side of the case, parallel to the dial, as viewed from the front.
connection, top: one in which the stem projects upward from the case, parallel to the dial (see Fig. 2). connector: the component that joins the stem to the case assembly. connector, jam nut: a connector using a straight-thread nut and seating part for connecting the thermometer to a bushing, flange, or thermowell. connector, plain: a connector with no threads. connector, threaded: a connector with fixed threads, usu- ally tapered. connector, union: a threaded fitting that is rotatable rela- tive to the case. correction: the quantity that is algebraically added to an indicated value to obtain the true value. The algebraic sign of correction is the opposite of the sign of the error (see also error). corrosion failure: see failure, corrosion. coupling nut: see connector, jam nut. crystal: see window. dampening: a method used to reduce the effects of shock and vibration, usually the application of a viscous mate- rial to the bimetallic element and/or bearing. dial: the component that contains the scale. dial, anti-parallax: see dial, mirror; dial, multi-plane. dial, dished: see dial, multi-plane. dial, dual-scale: a dial containing two scales with different units of measure, such as °F and °C. dial, graduations: the individual division marks of a scale. dial, mirror: a dial with a reflector band for the purpose of reducing parallax error. dial, multi-plane: a dial with graduations in approxi- mately the same plane as the pointer (to reduce parallax error). dial, rotatable: a feature that allows rotation of the dial relative to the pointer. diameter, stem: the outside diameter of the stem.