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Do ProSoft AFC Flow Computer solutions support "ASME MFc-6M", "API-11" and/or "API-12" calculation standards for measuring lubricating oils?

Article Number: 397 | Rating: Unrated | Last Updated: Wed, Dec 31, 2014 at 4:21 PM

The API-11 and API-12 calculations are available in ProSoft AFC Flow Computers, beginning with version 2.05.

MPMS Ch 12 specifies, essentially, the necessary factors and calculational sequence for measuring liquids, and the general method of measurement using pulse meters (e.g. turbines). For this case, this means that we must have or calculate the KF (K-factor), MF (meter factor), CTPL or CTL&CPL (correction of liquid volume for the effects of temperature and pressure), and CSW (correction for sediment and water), and apply those factors to the pulse train or pulse frequency input.

The KF and MF are configured parameters, one of which can be adjusted for flow rate effects using a linearization curve of up to 5 data points -- same as for gases using AGA 7; these are covered by MPMS Ch 12. The CTPL for lube oils is calculated according to the procedures of MPMS Ch 11.1 (2004). The handling of water content (BS&W, correction factor CSW) for lube oils is according to the specifications of MPMS Ch 12.

When a pulse train is not available but an orifice is used, the flow rate is calculated using AGA 3 (or ISO 5167), and the need for KF and MF and the handling thereof disappears.

API 2540 was originally an alternate designation for the older MPMS Ch 11.1, which specified the calculation of CTL only. As CTL and CPL almost always go hand in hand, exemplified by their collapse into a single CTPL by the 2004 edition, the term "API 2540" has come to mean in casual conversation any collection of standards that specifiy the calculation and uses of CTL, CPL, and CSW, namely "liquid correction factors". So, colloquially, API 2540 means MPMS Chapters 11 and 12.

In cases where a Coriolis meter is used, we are not sure whether a pulse train from a Coriolis meter would give any better measurement than the flow rate from the meter, which could be taken directly as the AFC's Primary Input by configuring the channel for flow rate integration. If flow rate is used, I believe that the mass rate would be preferable to the volume rate, as the mass (IIRC) is more closely related to the meter's raw readings than the volume (which would be calculated from the mass using the density). In any case, the T&P are necessary in order to calculate CTPL, and unless the lube oil is refined and on spec enough to configure to the AFC a reliable Standard Density (density at base or reference conditions) the Density from the meter (at operating conditions) is also necessary.

The standard ASME MFc-6M (1998 edition) is titled "Measurement of Fluid Flow in Pipes using Vortex Flowmeters". The AFC does not implement this standard specifically, so it cannot use the raw frequency of the vortex pairs to calculate flow. Howver, if the Vortex meter is a "smart" meter and can use its on-board electronics to convert its raw readings to a flow rate or a pulse train, then it can be treated by the AFC just like any other "smart" meter that produces a similar primary input, such as Coriolis or Ultrasonic meters.

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