API MPMS 7:2001(2012) pdf download
API MPMS 7:2001(2012) pdf download.Manual of Petroleum Measurement Standards Chapter 7-Temperature Determination.
3.13 total-immersion thermometer: A liquid-in-glass thermometer designed to indicate temperatures correctly when just that portion of the thermometer containing the liquid is exposed in the temperature being measured.
3.14 transient: As used in this standard, refers to highvoltage, fast-rising, lower-energy pulses. The disturbances caused by transients usually have duration of 0.2 seconds.
4 Significance and Use
Temperature has the most significant effect on the accurate determination of liquid quantities when correcting to standard conditions for custody transfer and inventory control purposes. As a result, the most accurate means for temperature determination should be used for these applications.
The average temperature of a liquid is required to calculate its volume at a standard temperature, so it is imperative that temperatures be detcrm i ned accurately.
For custody transfer, the means of temperature determination should be agreed to among the parties involved.
This standard presents both Metric (SI) and US Customary units, and may be implemented in either system of units. The presentations of both units are for convenience of the user, and are not necessarily exact conversions. The units of implementation are typically determined by contract, regulatory requirement. the manufacturer, or the user’s calibration program. Once a system of units is chosen for a given application, it is not the intent of this standard to allow arbitrarily changing units within this standard.
5 Equipment and Apparatus
Many types of temperature devices are available. The temperature device used must he selected to match application requirements. Considerations should include temperature range, scale (°C or °F) response time, accuracy, discrimination, repeatability, and ambient temperature and atmospheric conditions where the device is installed. The ultimate use of the temperature data must also be considered.
Accuracy requirements, mechanical limits. operating limits, ambient conditions, and individual preferences must be considered when selecting a temperature device to be used for temperature determination on a metered stream or meter prover. In addition, the ability of the device to sense and record the actual temperature of a liquid to the specified temperature increments (temperature discrimination) must be evaluated. API MPMS Chapter 12 provides temperature discrimination requirements for various measurements and calculations.
The use of a temperature device that can perform to a more stringent discrimination than required in Chapter 12 is acceptable and preferred. However, the selection, installation, maintenance, operation. and calibration of such equipment must be adequate to ensure temperature-device performance to the level chosen and agreed to by all parties involved.
The following general precautions affect the accuracy and performance of all types of All’ systems. These precautions should be observed where they are applicable.
• All All’s should be capable of withstanding the pressure, temperature, and other environmental conditions likely to be encountered in the designated service. When an AT!’ is installed in a corrosive service, any parts exposed to the liquid or vapor should be of durable, corrosion-resistant construction to avoid bcth product contamination and AT!’ corrosion. All All’s should be sealed to withstand the vapor pressure of liquid in the tank. All’s mounted on marine vessels with an inert gas system (IGS) should be designed to withstand the operating pressure of the IGS.
• Compatibility—To avoid both product contamination and equipment corrosion, all pails of the All’ equipment in contact with the product should be compatible with the product. The Al]’ equipment should be designed to meet the operating conditions.
Note 1: This protection may require mounting the AlT sensor(s) in a thermowell.
Note 2: All’ sensors can be an integral part of the automatic tank gauging system (ATG) level sensor assembly (e.g., float and tape, pole). Sonie designs (e.g.. float and tape) may need the level/temperature sensor assembly to be raised to a “store” position when it is not being used. Note thai such All’s cannot be used during tank washing on marine vessels.
• All marine All’s should be specified and installed in accordance with the appropriate National and/or International (IMO, USCG. IEC, NEC, ISGOTT, ISO, etc.) marine electrical safety standards.
• ATfs should be certifIed for use in the hazardous area classification appropriate to their installation.
• All external metal parts of All’s mounted on tanks should be firmly connected to an electrical earth. This will be the ship’s hull in the case of marine All’s.
• All All’ equipment should be maintained in safe operating condition and manufacturers’ maintenance instructions should be complied with.
