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『Flow Meter Accuracy Class 0.15 Error Calculation and Proving Formulas for Custody Transfer』Related information(v cone flow meter|rotary gas meter|gallon meter|gear meter|metal tube rotameter|glass tube rotameter|nutating disk meter|transit time ultrasonic flow meter|wedge flow meter|pd meters|hydraulic flow meter|ultrasonic water flow meter|water flow meter|air flow meter|magnetic water flow meter|oxygen flow meter|gas flow meter|argon flow meter|air velocity meter|gasoline flow meter|fuel flow meter|ultrasonic water meter|digital water meter|nitrogen flow meter|solid flow meter|Oxygen tank flow meter|digital water flow meter|diesel fuel flow meter|steam flow meter|02 flow meter|compressed air flow meter|oil flow meter|liquid flow meter)
Flow Meter Accuracy Class 0.15 Error Calculation and Proving Formulas for Custody Transfer
Quick Answer: Class 0.15 accuracy means the meter has a maximum permissible error of plus or minus 0.15 percent of measured value under reference conditions. Custody transfer proving checks the flow meter against a certified master meter or a pipe prover and applies a meter factor. The basic error calculation compares the indicated flow value to the reference flow value using a simple percentage formula.
What Class 0.15 Accuracy Really Means
Accuracy class 0.15 is a tight specification. In many custody transfer applications, the acceptable accuracy is 0.2 percent or 0.3 percent. Class 0.15 is better than that. A flow meter with this class must hold the error within plus or minus 0.15 percent of rate. This applies to liquid fuels, chemicals, refined products, LNG, and some food grade liquids. Silver Instruments supplies Coriolis mass flow meters that meet 0.15 percent of rate for many fluids.
Error Calculation Formula for Class 0.15 Flow Meters
Use this formula to calculate the measurement error of a flow meter. E percent equals (Q indicated minus Q reference) divided by Q reference times 100. Q indicated is the flow rate shown by the meter. Q reference is the flow rate from a certified reference device. A meter with a reference flow of 5000 kg/h and an indicated flow of 5006 kg/h has an error of 0.12 percent. That passes Class 0.15. An indicated flow of 5010 kg/h gives an error of 0.2 percent. That fails Class 0.15. Simple and useful for site checks.
Proving Formulas Used in Custody Transfer
Custody transfer proving usually uses a master meter or a prover. The meter factor formula is MF equals V reference divided by V meter. V reference is the volume or mass total from the certified reference. V meter is the total from the flow meter under test. If the reference total is 1000 liters and the meter total is 1001.5 liters, the meter factor is 0.9985. Apply this factor to future batch totals for billing and tax purposes. Some sites use a bidirectional ball prover. Others use a gravimetric weigh scale for mass proving. We often see this on marine fuel loading and chemical export lines.
Which Flow Meter Types Meet Class 0.15 for Custody Transfer
Coriolis mass flow meters are the main choice for Class 0.15 custody transfer. Silver Instruments Coriolis meters measure mass flow directly in kg/h. They also provide density in kg per cubic meter and temperature in °C from the same device. Electromagnetic flow meters typically reach 0.2 percent to 0.3 percent of rate. Ultrasonic flow meters may reach 0.3 percent to 0.5 percent depending on pipe conditions. Oval gear flow meters are common for diesel and fuel oil, but most models are 0.2 percent or 0.5 percent. For a true 0.15 class system, Coriolis is the safe selection. The output can be 4-20 mA HART, Modbus RTU, or pulse. For hazardous areas, we supply ATEX Zone 1 and Zone 2 approvals.
A Field Example from a Customer Site
Last year a customer in Vietnam asked us for a custody transfer skid for diesel loading. The line was DN50. Normal flow was 3000 kg/h. Peak flow was 8000 kg/h. Operating pressure was 20 bar. Diesel temperature was around 40 °C. Viscosity was 5 cP at that temperature. We supplied a Silver Instruments Coriolis mass
Contact Silver Instruments for a Custody Transfer Flow Meter Quote
Send us your fluid name, density, viscosity in cP, pressure in bar, temperature in °C, pipe size in DN, and flow range in kg/h. Include your hazardous area classification if the site has ATEX Zone 1 or Zone 2. Our engineers will select a Class 0.15 Coriolis mass flow meter or another suitable model for your custody transfer application. Contact Silver Instruments today. Tel: +86-25-68650347. Whatsapp: +86-25-52155837. WeChat: +86 15365082610. Our website is flow-meter.com.au.
FAQ: 5 Key Questions on Class 0.15 Custody Transfer Flow Meters
What flow meter types can achieve Class 0.15 accuracy?
Coriolis mass flow meters from Silver Instruments can meet 0.15 percent of rate for liquids and gases in custody transfer. Some hygienic Coriolis models go down to 0.1 percent under stable conditions. Electromagnetic flow meters typically reach 0.2 percent or 0.3 percent. Ultrasonic and oval gear meters may reach 0.2 percent to 0.5 percent depending on the model. For Class 0.15, our standard recommendation is a Coriolis mass flow meter with 316L stainless steel wetted parts.
How is custody transfer proving done in the field?
A meter under test is compared to a certified master meter or a bidirectional prover. The totalized pulses from the test meter and the reference device are collected over the same run. Then the meter factor is calculated as MF equals V reference divided by V meter. This factor is applied to future batch totals. For mass measurement, a mass prover or a weigh scale gives the reference mass.
What is the difference between percent of rate and percent of full scale?
Percent of rate means the error is calculated from the actual flow rate. Percent of full scale means the error is calculated from the full scale span. A 0.15 percent of rate meter on a 1000 kg/h range has an error of 1.5 kg/h at 1000 kg/h and 0.75 kg/h at 500 kg/h. This matters in custody transfer because many meters lose accuracy at low flow. Our application engineers always confirm whether the accuracy statement uses rate or full scale.
What data do I need to send for a Class 0.15 custody transfer flow meter quote?
Send the fluid name, density, viscosity in cP, process pressure in bar, process temperature in °C, line size in DN, flow range in kg/h, and the hazardous area classification such as ATEX Zone 1 or Zone 2. If the meter will be used for LPG or LNG, include the proving method and the reference standard your region accepts.
Can Silver Instruments provide calibration certificates for custody transfer?
Yes. We provide factory calibration certificates traceable to international standards. Each Coriolis meter is wet calibrated or dry calibrated at our facility. For custody transfer in countries such as Vietnam, Indonesia, Saudi Arabia, Nigeria, or Chile, we can supply additional third party certification when requested. We also have service partners in several regions for local verification.