『Flow Meter Oxygen Parts Diagram: Identification of Knobs, Needle Valves, and Thorpe Tubes』Related information(flow rotameter|digital flow meter|balo meter|hydraulic flow meter|volumetric meter|positive displacement meter|pitot tube flow meter|displacement meter|cfm meter|variable area flow meter|inline flow meter|differential pressure flow meter|calibrated flow meter|velocity meter|paddle wheel flow meter|oval gear flow meter|anemometer hvac|multiphase flow meter|doppler flow meter|thorpe tube flowmeter|heat flow meter)
Flow Meter Oxygen Parts Diagram: Identification of Knobs, Needle Valves, and Thorpe Tubes
Quick Answer: A typical industrial oxygen flow meter diagram shows a Thorpe tube, a control knob, a needle valve, a float, and inlet and outlet ports. The knob moves the needle valve to adjust flow. The Thorpe tube gives direct visual reading of oxygen flow. For oxygen service you must verify wetted materials, cleaning procedure, and connection size before ordering.
Why the Parts Diagram Matters for Oxygen Flow Meter Selection
Plant engineers in Southeast Asia and the Middle East often ask for a flow meter oxygen parts diagram before they request price. They want to see the needle valve position, the tube type, and the connection orientation. In practice a clear diagram reduces wrong purchases. We have seen customers order a general air rotameter for oxygen and later find the O ring material was not compatible. Oxygen service is stricter than air service. You need clean parts, no oil, no grease, and usually 316L stainless steel or PTFE wetted surfaces. The identification of knobs, needle valves, and Thorpe tubes is the first step before you compare price or delivery time.
Thorpe Tube Location and Reading
The Thorpe tube is the transparent vertical column. It holds a float that moves up as flow increases. In most oxygen flow meters the tube is borosilicate glass with a printed scale in L/min or SCFH. A common industrial range is 0 to 15 L/min for ozone generators. Larger units go to 0 to 100 L/min for oxygen lancing in foundry operations. The tube may sit inside a polycarbonate shield if the meter is installed near walkways. You identify it by the graduated markings and the float inside. If the tube is cracked, replace it. Do not run compressed oxygen through a cracked tube. A customer in Vietnam replaced only the float after a pressure spike and still had unstable readings because the tube seat was worn.
Needle Valve Function and Identification
The needle valve is a precision flow control component. It has a fine threaded stem and a tapered needle that moves into an orifice. On an oxygen flow meter the needle valve can be located below the tube or integrated into the base block. You identify it by the small stem, the seat, and the slow change in flow when you turn the knob. Needle valves for oxygen often use a 316L stainless steel needle and a PTFE seat. Some low cost units use brass, but brass is not always accepted for humid oxygen. The valve should be oxygen cleaned per ASTM G93 or equivalent. On process sites we recommend a needle valve with a metal to metal seat if the oxygen stream contains particles. Otherwise a soft PTFE seat gives a tight shutoff.
Control Knob Identification
The control knob is the part that the operator rotates. Most industrial oxygen flow meters use a phenolic or nylon knob. Some use stainless steel knobs for harsh areas. The knob connects to the needle valve stem by a set screw or a molded thread. Here is the thing: the knob is often the first part to crack because operators overtighten it. We keep spare knobs for DN15 and DN20 oxygen rotameters. If you open a typical parts diagram, the knob is usually labeled as item K or KN. The thread can be M6 or 1/4 inch depending on the valve stem. Send us a photo of the broken knob and the valve stem diameter. We can ship a replacement from Jiangsu or our Australia stock.
Connection Ports, Flow Ranges, and Materials
Check the inlet and outlet connection size before you order. Common sizes are 1/8 inch NPT, 1/4 inch NPT, G1/4, or DN6 tube fittings. Industrial oxygen panels often use compressi
Common Applications for Oxygen Flow Meters
We see these units in ozone generation, wastewater treatment, aquaculture, oxygen lancing, laboratory gas mixing, and metal cutting. Each application has a different connection and cleaning need. Ozone gas is aggressive. Fish farms in Vietnam often use simple low flow meters with 0 to 15 L/min range. Cylinder filling stations in Nigeria ask for higher pressure ratings and metal needle valves. A brass needle valve may pass a quote review but fail on site when humid oxygen condenses. That is why the parts diagram and material list matter more than the outer housing. For a gas mixing skid in ATEX Zone 1, confirm area classification before you choose a plastic body rotameter.
FAQ on Oxygen Flow Meter Parts Identification
What is the difference between a Thorpe tube and a rotameter tube?
A Thorpe tube is a type of variable area tube often used in oxygen service. It has a direct reading scale and a float. In many process plants the term rotameter is used for the whole meter. We use the same identification method for both.
Can I replace only the needle valve or knob?
Yes. We keep needle valves and knobs as spare parts. You need to send the meter model, tube size, and valve stem thread. A photo helps.
What flow range should I specify?
Give normal, minimum, and maximum flow in L/min or SCFH. Also state oxygen pressure in bar and temperature in °C. For oxygen dosing a 0 to 15 L/min range is common. For aeration or lancing you may need 0 to 60 or 0 to 100 L/min.
Does the parts diagram show wetted materials?
Usually the diagram shows part positions only. The material list is separate. Confirm O ring material, valve body, and tube glass. For oxygen always request oxygen clean assembly.
Do you ship oxygen flow meter parts to Southeast Asia and Latin America?
Yes. We ship from China to Vietnam, Indonesia, Thailand, Chile, Peru, UAE, Saudi Arabia, and other countries. Spare parts can be quoted by DHL or sea freight.
Contact and Quotation Details
Silver Automation Instruments supplies industrial flow meters and spare parts. To get a quotation for an oxygen flow meter or spare parts, send us your flow range in L/min, oxygen pressure in bar, temperature in °C, connection size in DN or inch, and a marked parts diagram if you have one. Tel: +86-25-68650347. WhatsApp: +86-25-52155837. WeChat: +86 15365082610. We reply within 24 hours on business days. Mention your city and application. For example a fish farm in Indonesia needs different materials than a cylinder filling station in Saudi Arabia.
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