Lease Automatic Custody Transfer per API MPMS Ch. 6.1
Custody transfer regulations, meter rangeability, MPMS uncertainty stack-up, sampling per API 8.2, prover sizing per MPMS Ch 4.
Meter rangeability constraint:
Prover size (API MPMS Ch. 4):
Air eliminator (API MPMS 6.1):
Sample grab volume (API MPMS 8.2):
System uncertainty (RSS):
A Lease Automatic Custody Transfer (LACT) unit is a skid that measures and transfers custody of crude oil from a lease or tank battery to a pipeline or transporter. Per API MPMS Ch. 6.1 it contains a strainer, air eliminator, BS&W monitor with auto-divert, sampler, custody meter, and a prover connection.
Pick a meter type whose published flow range brackets your minimum and maximum LACT throughput within its rangeability: PD ~10:1, turbine ~10:1, Coriolis 100:1 to 1000:1, ultrasonic ~30:1. Coriolis is preferred when API varies > ±2°.
Auto-divert is typically armed at 1.0% BS&W with a 30-second delay. Pipeline acceptance specs are usually 0.5–1.0%; the diverter must keep the meter from logging off-spec oil to custody totals.
Small Volume Provers (SVPs) come in 0.5, 1.0, 2.0, 5.0, and 10 bbl base volumes. The prover must accumulate at least ~10,000 meter pulses per pass for ±0.025% repeatability per API MPMS Ch. 4.