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Diesel Oil Flow Meter DN50 Flange Connection Standards
Quick Answer: When you select a diesel oil flow meter with DN50 (2 inch) flange connections, the three standards you will meet most often are ASME B16.5 Class 150, EN 1092-1 PN16, and JIS 10K. Silver Instruments builds oval gear flow meters with integrated flanges that match these standards, so your installation team fits the meter without adapter spools. Send us your flow range in L/min, operating pressure in bar, diesel temperature, and the flange standard your pipe uses to get a final model and price.
DN50 is a workhorse size in diesel monitoring. It lives in fuel transfer lines between day tanks and generators, in truck loading gantries, and on marine fuel manifolds. The flange connection standard you pick affects bolt pattern, gasket surface, and pressure rating. A mismatch means extra fittings or a drip on startup. Because our customers in Southeast Asia and the Middle East often mix European and American equipment, we pre-build oval gear meters with multiple flange options. That removes guesswork from the purchase.
Flange Standards for DN50 Diesel Meters
Most diesel applications run below 20 bar. A fuel depot in Vietnam often uses EN 1092-1 PN16 flanges. A power plant in Nigeria that sources US-made pumps usually needs ASME B16.5 Class 150 RF (raised face) connections. A fishing vessel refit yard in Indonesia may request JIS 10K flanges. The DN50 nominal diameter maps to 2 inch in ASME and 50A in JIS, but the flange outer diameter and bolt circle are not interchangeable. A PN16 DN50 flange has a bolt circle of 125 mm with four M16 bolts. A Class 150 2 inch flange has a bolt circle of 120.65 mm with four 5/8 inch bolts. You cannot swap them without adapter plates. That is why we stock three variants. No special machining, no delay.
The pressure-temperature rating matters too. A carbon steel Class 150 flange rates for about 19.6 bar at ambient temperature. PN16 holds 16 bar up to 120 degree C. Diesel temperature rarely exceeds 80 degree C in engine rooms, so both are safe. In practice, most engineers skip the derating chart and just match the piping class. A customer in Thailand ordered a PN16 meter for a 12 bar diesel supply. It passed the hydrotest without a single issue. If you pump diesel above 30 bar, ask for a PN40 or Class 300 flange. Our oval gear meter bodies are machined from solid bar stock, so higher ratings do not force a complete redesign.
Why Oval Gear Meters Win for Diesel
Diesel viscosity sits between 2 and 5 cP at 40 degree C. That is the sweet spot for positive displacement oval gear meters. Turbine meters slip at low flow rates. Coriolis meters deliver extreme accuracy but cost more and need zeroing routines. The oval gear design gives repeatability of plus minus 0.1 percent and a typical accuracy of plus minus 0.5 percent of reading on a DN50 body. It handles flow ranges from 2 L/min up to 200 L/min. The output is a raw pulse signal. You wire it to a batch controller or a panel meter. Silver Instruments oval gear flow meters use a cast iron or stainless steel housing with hard chrome-plated rotors. For diesel, cast iron with aluminum rotors works well and keeps the price accessible.
We saw a seafood processor in Chile replace their turbine meter with our oval gear unit for bunker diesel. They reported zero maintenance over 18 months. Because the oval gear has no bearings in the flow stream, abrasive particles do not cause instant failure. The moving parts are driven by external gears in a separate chamber. This design keeps diesel flowing even with small impurities. We still recommend a Y-strainer or 200-micron filter upstream for heavy sediment. Common sense on fuel lines, nothing exotic.
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DN50 flange faces are typically raised face. For diesel, use a non-asbestos fiber gasket or a PTFE envelope gasket. Do not over-tighten the bolts. Tighten cross pattern to 25 Nm for M16 bolts. The meter works in horizontal or vertical lines, but you must keep the measuring chamber full. We always suggest a pulse dampener or a small air release valve at the high point when you measure diesel that tends to foam. Straight run requirements are not needed for oval gear meters. You can mount it right after a 90-degree elbow. That saves space on a skid.
Temperature compensation matters when diesel density changes. Our DN50 meters can include a PT100 sensor and a flow computer with 4-20 mA HART output. The corrected totalized value appears on a local display. We shipped this option to a fuel depot in Oman where daily ambient swings go from 18 degree C to 45 degree C. The API-corrected volume gave them a more accurate inventory. If you need ATEX Zone 1 certification for a gas station or a fuel terminal, specify it at order. Our meters carry ATEX II 2G Ex ia IIC T4. No external Zener barriers needed.
FAQ Diesel Oil Flow Meter DN50 Flange Standards
Q: Can I get a DN50 meter with both ANSI 150 and EN PN16 drilling on one flange?
A: We do not offer dual-drilled flanges on DN50 oval gear meters. The bolt circles overlap. You pick one standard and we supply the meter with a certificate of conformance for that flange dimension. Mating is direct.
Q: What is the maximum flow for a DN50 oval gear diesel meter?
A: Up to 250 L/min for continuous duty. The usable range goes down to 2 L/min with good accuracy. If your peak flow exceeds 300 L/min, step up to DN80. We size it based on your average operating point, not the absolute maximum.
Q: Do you provide a flange gasket and bolts with the meter?
A: We ship each DN50 meter with a standard non-asbestos gasket and a set of four carbon steel bolts with nuts. For offshore and marine, we can supply stainless steel bolts. State your requirement when you request the quote.
Q: How do I order a DN50 diesel meter with 4-20 mA and a local totalizer?
A: Mention the output option 4-20 mA plus pulse, battery-powered totalizer. The meter comes with a prewired junction box and an LCD display. You need a 24 VDC power supply. The analog signal gives flow rate. The pulse output gives volume.
Q: What material handles diesel with B20 biodiesel blend?
A: Cast iron housing with aluminum alloy rotors works for standard diesel. For B20 or higher blends, we recommend stainless steel rotors and PTFE-coated seals. The flange material stays carbon steel unless you request full stainless. Tell us your exact fuel specification and we advise on wetted parts.
Q: Do you have marine type approval for a DN50 fuel oil meter?
A: We can supply meters with DNV or BV type approval for fuel oil monitoring. Let us know the classification society and we will quote accordingly. The flange standard you choose must match the ship piping class.
To get a price for a diesel oil flow meter DN50 with the right flange connection, send your application details to our team. Tell us the diesel flow range (minimum and maximum in L/min or m3 per hour), the working pressure in bar, fluid temperature, and the flange standard you need. If you do not know the standard, take a photo of your pipe flange and we will identify it. Reach us at flow-meter.com.au or email directly. Silver Instruments delivers meters from stock for most DN50 ANSI 150 and EN PN16 combinations. Custom ATEX and marine versions ship in 10 to 15 days.