Sanitary Stainless Steel Oval Gear Flowmeter for Food and Beverage CIP Dosing

Built for plants that fill yogurt, dessert cream, fruit concentrate, syrup and edible oil into packs where every gram over the target is a direct loss. This meter measures the volume that actually passed through the line, in a chamber that can be cleaned in place, documented for audit, and switched between products without recalibration.

Sanitary 316L oval gear flowmeter with tri-clamp ports and sealed register head.

Second view: crevice-free hygienic body, no threaded pockets in the product path.

Why Filling Lines Outgrow Inferred Flow Measurement

Most filling lines start with a turbine or an electromagnetic meter, because both are cheap and familiar. Both infer the flow: the turbine from how fast its rotor spins, the electromagnetic meter from the voltage induced across a conductive liquid. Inference works while the product stays identical. It breaks the moment viscosity, temperature or aeration changes — and on a dairy or beverage line that happens several times a day, between product and CIP caustic.

The commercial consequence is measurable. A meter reading one percent low on a 200 g cup across 40,000 cups per shift gives away about 80 kg of product per shift, roughly 20 tonnes a year on a single line. The same error in the other direction produces overfill complaints, retail weight checks and rework in the packing hall. Engineers then spend weeks building viscosity correction tables that nobody fully trusts.

A positive displacement meter removes the inference. It traps a fixed volume of product between rotor and chamber wall, and counts how many times that volume is filled and discharged. Viscosity changes the pressure required to push the product through; it does not change how much product fits inside the chamber.

Two Working Conditions, Measured Side by Side

How the Measuring Chamber Counts Product Instead of Guessing It

Inside the chamber a pair of oval rotors rotates in mesh, driven only by the pressure of the product itself. As they turn, they close off a fixed crescent of volume at the inlet, carry it around the chamber wall, and release it at the outlet. Each revolution of the pair therefore displaces one known quantity of liquid, regardless of whether that liquid is water-thin caustic or dessert cream.

A non-contact pick-up senses each rotation and converts it into pulses. The calibration constant, expressed as pulses per litre, is measured on a gravimetric rig and printed on the certificate. Because the measuring element is a fixed geometric volume, the constant does not drift when the medium changes — that is the single most useful property on a line running six recipes a day.

Two secondary effects of the principle matter to engineers. First, the meter does not need a developed velocity profile, so no upstream or downstream straight run is required; it can sit between a valve block and a filler with elbows on both sides. Second, shear is low because the rotors turn slowly at a few hundred rpm, which is why this design suits products that must not be damaged by the pump or the instrument. Where a line cannot be opened for a spool piece, a clamp-on ultrasonic flowmeter is the usual temporary answer, although it needs a developed velocity profile and a clean, gas-free liquid.

Structural Features That Survive CIP, SIP and Back-to-Back Changeover

A general industrial gear meter and a sanitary one differ in five places, and each of them is a point where a food plant gets let down if it is missing:

• Single-piece 316L body with an internal surface of Ra 0.4 µm. Product contact area is smooth enough that residue does not anchor in machining marks.
• Clamped end covers with no threaded pockets. A tri-clamp joint opens with one clamp and leaves a flat, drainable face; threaded ports leave a spiral gap that CIP fluid reaches last and rinses first.
• Rotor support pins outside the flow path. Ceramic or carbide pins hold the rotors without bearing bores in the product stream, so there is no sump for product to sit in between batches.
• Seal options matched to the wash cycle. EPDM for standard CIP to 85 °C, PTFE or PTFE-encapsulated for SIP and acid rinse; both are supplied with FDA-compatible compound declarations.
• Full drainability. Mounted with the outlet facing upward, the chamber empties by gravity; the front cover opens with a single clamp for visual inspection between production runs.

Six Advantages That Matter on a Filling Line

Sizing, Installation and Commissioning Notes From the Engineering Desk

Size the meter on the lowest flow you must measure accurately, not on the highest. A DN25 chamber covers roughly 3–60 L/min; if the filling step runs at 12 L/min and the flush at 45 L/min, DN25 is correct, because a larger chamber loses resolution exactly where the batch is finished and the last few hundred millilitres are counted.

Keep 30–50 kPa of differential pressure available across the meter at working viscosity. Product that is degassed, aerated or drawn from a tank running low will give a low reading in any volumetric meter, so install the meter where the line stays full and, on horizontal runs, keep the rotor shaft axis horizontal so air cannot collect in the chamber.

Commission with a three-point check at your real fill rate, store one K factor per recipe, and set the batch controller to close the valve on the preset count rather than on time. Our engineers review the P&ID and the product data sheet before release and confirm size, seal compound, connection standard and output protocol in writing. Specifications for the rest of the family sit on our positive displacement flowmeter range page.

Installation layout (schematic drawing): no straight run required between valve block and filler.

Application Case 1: Dairy Group, Poland

Application Case 2: Beverage Concentrate Skid Builder, Mexico

Technical Specifications

Frequently Asked Questions

Can the meter be cleaned in place without disassembly?

Yes. The measuring chamber has no threaded dead pockets, the internal surface is finished to Ra 0.4 µm, and both end covers are fully drainable, so CIP caustic at 80 °C and the acid rinse reach every wetted surface. The rotors are supported on ceramic or carbide pins that tolerate the temperature swing of a wash cycle without seizing. For SIP duty we supply PTFE or PTFE-encapsulated seals rated to 140 °C. Two practical rules keep cleaning effective: mount the meter so the outlet faces upward to avoid air locks, and keep flush flow above 1.5 times the normal dosing rate so the chamber sees turbulent wash rather than a trickle. If your protocol requires verification, the front cover opens with one clamp for visual inspection between production runs.

Will it handle yogurt with fruit pieces or sauces containing pulp?

No, and we would rather say so before you order. A positive displacement oval gear meter measures by trapping a fixed volume between rotor and chamber wall, so particles larger than roughly one tenth of the rotor clearance will either jam the gears or pass through crushed — and a crushed particle changes the trapped volume, invalidating the reading. For clean, homogeneous products such as milk, cream, syrup, concentrate, wine, edible oil and CIP chemicals, the design is at its best. If your line carries fruit pieces, fibrous pulp or seeds, keep this meter on the clear-liquid side of the process or move the measurement to a mass flow meter. Our sizing team will tell you honestly which way to go, because a jammed meter costs more than the right instrument.

Electromagnetic, Coriolis mass, or oval gear for beverage dosing?

The three technologies answer different questions. Electromagnetic meters need a conductive liquid, so they are unsuitable for syrup, edible oil and alcohol, and they report volumetric flow that shifts with temperature. Coriolis mass meters measure mass directly and handle particulates, but the smallest sizes cost several times more and need a vibration-free installation. Oval gear meters deliver the lowest cost per accurately measured litre on clean, viscous or lubricating products, and they need no straight pipe run, which matters on compact filling skids. On a typical juice or dairy dosing line we recommend oval gear for batch accuracy and repeatability, with a mass meter kept as a reference instrument for periodic verification rather than as the working meter.

What documentation is supplied for food safety audits?

Every meter ships with a 3.1 material certificate for the 316L body and rotor set, a five-point calibration certificate traceable to a national volumetric standard, and a pressure test record at 1.5 times rated pressure. A declaration of conformity and a full dimensional drawing are issued with the order, which is usually what auditors and project engineers ask for first. We also provide seal compound declarations for the FDA-compatible EPDM and PTFE options, and a cleaning validation support sheet listing surface finish, drainability and temperature limits. If your QA team works to a specific template, send it before shipment and we will complete the paperwork in your format rather than ours.

Related Products and Further Reading

Choosing between measuring technologies is usually the harder decision, so these are the pages our engineers send to food and beverage customers most often:

• Positive displacement flowmeters — the full family: oval gear, rotary piston, twin rotor, reciprocating piston and gas versions.
• Stainless steel oval gear flowmeter with rotary seal — the 24 V DC version used where a control cabinet supplies power to the skid.
• Electromagnetic flowmeters — the right choice for conductive, water-based products where pressure drop must stay minimal.
• Ultrasonic flowmeters — clamp-on verification when a line cannot be opened for a spool piece.
• Case study: juice flow measurement in a sugar mill — how viscosity and temperature swings were handled on a food-grade line.

Need a sizing check against your own product data? Send the flow rate, viscosity and CIP temperature and we will come back with a size, a seal compound and a K factor.