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Quick Answer: Oval gear flow meters are positive rotary hardware that give repeatability of ±0.03 percent and accuracy of ±0.2 percent of reading for diesel, heavy fuel oil, lubricants, and clean viscous liquids. Pulse and 4-20 mA HART outputs connect to most PLC and batch controllers. Send us your fluid type, viscosity in cP, flow range, pressure in bar, temperature in °C, and pipe size in DN for a specific quote.
Oval gear meters belong to the positive displacement flow meter family. Two oval rotors mesh inside a precision chamber. Each rotation sweeps a fixed volume from inlet to outlet. That fixed volume is the reason the meter keeps high repeatability even when flow rate changes. In practice this matters for diesel dispensing, burner fuel feed, and oil blending. You get a pulse output that represents actual volume passed.
The hardware is simple. Rotors, shafts, bearings, and a pickup. But the tolerances matter. We saw a lubricant blending plant in Malaysia improve batch consistency by replacing turbine meters with oval gear units. Because the liquid viscosity was around 120 cP, the turbine output drifted at low flow. The oval gear meter held its K-factor across the batch. A paint manufacturer in the Philippines used the same approach on a solvent line.
Diesel transfer from day tanks to generators is common in Southeast Asia, Africa, and the Middle East. A DN15 or DN20 oval gear meter fits well because the flow rates are small, often 2 to 20 liters per minute. The meter body can be aluminum with FKM seals for diesel. For heavy fuel oil, we normally recommend cast iron or stainless steel with PTFE seals because the temperature at the meter can reach 90 °C or more. A PT100 sensor option gives you a temperature signal over the same 4-20 mA HART loop.
Marine bunker fuel measurement is another area. Some customers in the Pacific Islands use a DN50 oval gear meter on a portable bunker skid. Flow range from 50 to 500 liters per minute covers small vessel fueling. The oil is filtered before the meter. An air eliminator is installed upstream. This protects the rotors from overspeed and incorrect volume counts caused by entrained air.
Hydraulic oil, gear oil, and lubricating oil skids also benefit. Because oils tend to have viscosity from 20 cP to over 1000 cP, positive displacement meters do not rely on turbulent flow profiles. Most engineers skip this part. They just want a pulse per liter or a 4-20 mA output to a batch controller. Our standard pickup gives a pulse resolution that matches many PLC high-speed counter inputs.
Silver Instruments supplies oval gear flow meters in sizes from DN15 to DN80. Standard accuracy is ±0.2 percent of reading and repeatability is ±0.03 percent. That repeatability is the reason a fuel terminal in Vietnam switched to our SGO series for diesel loading bays. The previous meter drifted after temperature changes. The SGO with aluminum body and FKM seals held stable output.
Body materials include aluminum, cast iron, and stainless steel. Aluminum works for clean diesel, gasoline, and light oils. Cast iron suits heavy fuel oil because it handles higher pressure and temperature. Stainless steel works when the fluid is corrosive or when food grade oil is involved. Seal options include FKM, PTFE, and EPDM. Do not guess the seal material. Send us the fluid name, temperature in °C, and viscosity in cP. We will confirm compatibility.
Output options include pulse, 4-20 mA HART, and Modbus. The HART version is useful when you need flow rate and total flow from one loop. Local display options include a mechanical totalizer or an LCD. For ATEX Zone 1 areas, we can supply flameproof or intrinsically safe versions. Tell us the hazardous area classification and the gas group. We have supplied ATEX Zone 1 approved meters for LPG and solvent loading in the Middle East.
Here is the thing. Positive displacement meters are not tolerant of dirt or air. Install a strainer or filter upstream. Use an air eliminator if the fuel source can trap air. For diesel with a return line, make sure the meter sees a full pipe and stable back pressure. Never run the meter dry at full speed. That can damage rotors quickly.
We have seen this on customer sites many times. A pump starts before the inlet valve is fully open. The rotor spins up and the meter reads high or the bearing wears. Add a start delay or a control valve interlock. The cost of the meter is small compared to the cost of a failed batch or a tank overflow.
Piping size does not have to match the meter exactly. You can install a DN25 oval gear meter in a DN50 line with reducers. But watch the pressure drop. High viscosity oil at high flow through a small meter can push pressure drop past 1 bar. For heavy fuel oil, keep velocity through the meter within the datasheet limits. We will send you the pressure drop chart for your flow range.
We are based in China and ship to industrial users and distributors in Southeast Asia, Oceania, Latin America, Africa, and the Middle East. Because we focus on flow measurement hardware, we keep standard sizes in stock. Lead time for standard DN15 to DN50 aluminum oval gear meters is often 3 to 5 working days. Stainless steel and ATEX versions need longer.
The price point matters for small and medium enterprises. You get industrial grade accuracy without buying a Coriolis meter for simple fuel transfer. But if you need true mass flow, see our Coriolis mass flow meter range on the main site. For high repeatability fuel and oil measurement, an oval gear meter is usually the most practical choice.
So send us your pressure (bar), temperature (°C), pipe size (DN), and flow range. Tell us the fluid type and viscosity in cP. We will reply with a model number, price, and lead time. Contact Silver Automation Instruments by phone at +86-25-68650347, WhatsApp at +86-25-52155837, or WeChat at +86 15365082610.
Can an oval gear meter measure diesel, gasoline, and heavy fuel oil with the same unit?
Yes, if the seal and body materials fit all three fluids. But gasoline and heavy fuel oil have different viscosity and temperature ranges. Check the seal compatibility. We normally recommend one meter model for diesel and light oils, and a different body and seal set for heavy fuel oil above 80 °C.
What is the minimum flow rate for a DN25 oval gear flow meter?
A typical DN25 meter covers 1 to 100 liters per minute depending on viscosity. For very low flow, a DN15 meter works better. Send us your minimum and maximum flow rate in liters per minute and your viscosity in cP.
Do I need a filter before the oval gear meter?
Yes. Install a strainer or filter with mesh size fine enough to protect the rotor clearance. For diesel, a 100 micron strainer is a common starting point. For heavy fuel oil, follow the viscosity and temperature to avoid high pressure drop.
Can you supply oval gear flow meters for ATEX Zone 1 fuel skids?
Yes. We supply pulse and 4-20 mA HART versions for ATEX Zone 1 when the ordering code includes the hazardous area approval. Give us the zone, gas group, and temperature class.
What information should I send for a quote?
Send your fluid type, viscosity in cP, flow range in liters per minute or m3/h, pressure in bar, temperature in °C, pipe size in DN, output signal, and hazardous area class. That is enough for a complete selection.
