API MPMS 4.9.4:2010 pdf download

API MPMS 4.9.4:2010 pdf download.Manual of Petroleum Measurement Standards Chapter 4- – -Proving Systems Section 9- -Methods of Calibration for Displacement and Volumetric Tank Provers Part 4- -Determination of the Volume of Displacement and Tank Provers by the Gravimetric Method of Calibration.
Revenfication (or calibration) of the scale(s) is necessary due to:
— weigh scale relocation,
— weigh scale out of level during the procedure,
— change in volume (total mass) to be weighed by ±20 %,
— over-ranging the weigh scale,
— loss of power to weigh scale.
NOTE Refer to the weigh scale manufactures detailed instructions and recommendations for calibrations.
5.2.6.6 Draining of the Container
A container may be drained in any manner that does not effect the level or position of the weigh scale. Pumping the water from the container is allowed, but the pump or discharge hose must be removed before taring or refilling. The container may retain residual water after draining, provided that the weigh scale is tared before the next fill sequence. Note that the amount of residual water should be minimal and must not be enough to make the next total mass outside of the target mass.
5.2.6.7 TaringlZeroing the Weigh Scale
A weigh scale may indicate a mass reading with no mass applied. The weigh scale would then be tared (zeroed) before a weighing of water. A tare can also be performed with a significant amount of mass on the weigh scale. The reason to tare with a mass applied would be to obtain a net change in mass.
The weigh scale should be tared/zeroed before:
— verification,
— calibration,
— placing the container on the weigh scale,
— each weighing sequence during the calibration.
5.2.7 Water Quality
5.2.7.1 General
Ideally, for gravimetric calibrations, distilled or deionized water should be used. Water density is very important in gravimetric calibrations. Dirty water, heavily aerated water, hydrocarbon contaminated water, salt water, or any water of inferior quality, cannot be used (see Section 3 for water definitions). The density of the distilled or deionized water can be found in numerous tables. The algorithms developed by Patterson and Morris are currently used in petroleum industry standards.
For purposes of this standard, the density of water that has been defined as “reference water” can be obtained from the Patterson Morris algorithms in API MPMS Ch. 11.4.1. The “reference water” must be from a distilled, deionized or reverse osmosis source with a maximum conductivity of 50 j.iS.
Potable water from an approved public water (potable) supply may be used as calibration water in this procedure if “reference water” is unavailable (see definition in Section 3). If the density of the potable water exceeds 50 the 5.2.7.2 Water Conductivity Measurement
Water conducts electricity to some degree. Adding impurities that dissolve in the water such as salts increases its conductivity. Therefore, conductivity measurements can be used to correlate dissolved solids in solutions. Correlations improve as solids concentration and solids types are limited or similar.
Conductivity meters are common and typically simple instruments to operate. A meter for this standard:
— must be temperature compensated,
— indicate in the international unit of measure for conductivity, microsiemen (iS),
— indicate in increments of one for solutions below 75 iS, and
— indicate in increments of 10 or less for solutions above 75 jiS.
Conductivity meter/measurement recommendations:
— use commercially-available standard and traceable solutions for calibration/verification,
— ensure no bubbles or particulate matter is in test solution,
— ensure meter (probe or cell) is properly immersed in test solution,
— ensure no salts or particulate matter is allowed to build up on probes or cells,
nnse meter with deionized or distilled water before storage and any test sequence,
— follow manufactures recommendations for storage and calibration.
5.2.8 Air
Air must be vented from all high points in the system before beginning the calibration. The prover calibration depends upon a true hydraulic displacement, which is only possible in an air-free system. If air is found during a calibration pass, that pass is invalid and must not be used in the volume determinations. If air is found after the last calibration pass the complete calibration sequence is invalid and must be repeated.
5.2.9 Flow Rates During Calibration of Displacement Provers
Calibration flow rates should be chosen so that the displacer will have a steady continuous movement throughout the calibration pass. During all calibration passes it is desirable to keep the displacer moving smoothly at a constant flow rate. If the flow must be stopped at any time (e.g. waiting to empty container), the displacer should be stopped and restarted smoothly and quickly.