API - MPMS 7 ADD 1
Manual of Petroleum Measurement Standards Chapter 7 - Temperature Determination
|Publication Date:||1 October 2011|
This chapter describes the methods, equipment, and procedures for determining the temperature of petroleum and petroleum products under both static and dynamic conditions. This chapter discusses temperature measurement requirements in general for custody transfer, inventory control, and marine measurements. The actual method and equipment selected for temperature determination are left to the agreement of the parties involved.
Temperatures of hydrocarbon liquids under static conditions can be determined by measuring the temperature of the liquid at speciÞc locations. Examples of static vessels are storage tanks, Þeld gathering tanks, ships, barges, tank cars, tank provers, and test measures. Three methods are available for determining average static tank temperatures for custody transfer.
• Automatic method using fixed electronic temperature sensors.
• Manual method using portable electronic thermometers.
• Manual method using mercury-in-glass thermometers.
The automatic method covers the determination of temperature using Þxed automatic tank temperature (ATT) systems for hydrocarbons having a Reid Vapor Pressure at or below 101 kPa (15 pounds per square inch absolute). ATT systems include precision temperature sensors, Þeld-mounted transmitters for electronic signal transmission, and readout equipment.
The manual method covers:
• nonpressurized tanks and marine vessels
• blanketed tanks and marine vessels
• tanks and marine vessels that have been made inert and are under pressures of less than 21 kPa (3 pounds per square inch gauge)
It does not cover hydrocarbons under pressures in excess of 21 kPa (3 pounds per square inch gauge) or cryogenic temperature measurement, unless the tank is equipped with a thermowell .
Temperatures of hydrocarbon liquids under dynamic conditions can be determined by measuring the temperature of the liquid as it is flowing through a pipe. Dynamic temperature can be determined automatically or manually using electronic temperature devices or mercury-in-glass thermometers. The use of thermowells may be required in dynamic measurement to isolate the liquid material from the temperature sensor.
The requirements of this chapter are based on practices for crude oils and petroleum products covered by API MPMS Chapter 11.1 (ASTM D 1250). Requirements in this chapter may be used for other fluids and other applications. However, other applications may require different performance and installation specifications.