Oct 8, 2026Buying Guides
Inch vs Metric Flaring Tools: Avoid Size Mismatches When Buying
Compare CT-191A inch and CT-191M metric sizes, avoid approximate substitutions, and prepare a sample approval checklist for wholesale flaring tool orders.
An inch flaring tool and a metric flaring tool can look alike while serving different tube outside diameters. For distributors ordering a mixed range, the practical question is not which unit system is better: it is which exact sizes your customers use, and whether those sizes appear on the model you intend to buy.
Start with the tube outside diameter
Ask customers or your technical buyer for the tube outside diameter, material, wall thickness and fitting specification. A rounded conversion is not a tooling specification. For example, 1/4 inch equals 6.35 mm, not 6 mm; 3/8 inch equals 9.525 mm, not 10 mm; and 5/8 inch equals 15.875 mm, not 16 mm. These arithmetic conversions explain why a nearby metric marking is not proof of an approved substitute. Use the exact specified size and confirm the intended tube and connection with the supplier.
Worked example: CT-191A versus CT-191M
Our 2026 HVAC catalogue lists CT-191A for 3/16, 1/4, 5/16, 3/8, 7/16, 1/2 and 5/8 inch. CT-191M is listed for 5, 6, 8, 10, 12, 14 and 16 mm. Both are listed as 45-degree flaring tools. The lists describe separate versions; they do not mean that one clamp bar covers both sets of sizes.
For an order serving customers using 1/4-inch tube, specify CT-191A and that exact requirement. For customers using 6 mm tube, specify CT-191M and 6 mm. If both are needed, request separate model quantities and clearly labelled packaging. Do not order a general “small tube flaring tool” and leave the size system unstated.
See the complete model and carton data: https://www.nbtorchmark.com/products/ct-191a-ct-191m-45-degree-flaring-tools
The flare shape is a separate purchasing decision
Confirm the required flare angle and form from the fitting or equipment specification. A 45-degree listing does not establish suitability for 37-degree connections, double flares or bubble flares. A catalogue diameter range also does not prove suitability for every tube material and wall thickness. Obtain application-specific confirmation before describing a tool as suitable for your customers’ systems.
Approve a sample before fixing the assortment
Record the model and its markings, then check the sample using the intended tube and the approved operating instructions. Confirm the tube is held correctly and evaluate the finished flare against the fitting or equipment requirements. Record the sample identity and the buyer’s acceptance criteria so that a later shipment can be compared with what was approved. This is a purchasing checklist, not an installation or pressure-testing procedure.
For a mixed order, ask for a packing list that identifies inch and metric quantities separately. Confirm the labels on the tool, individual pack and carton use the same model designation. Keeping the versions distinct helps warehouse staff pick the correct item without relying on photographs.
Prepare a quotation that can be compared
Send quantity by model, required tube sizes, destination, packaging and branding requirements. Our minimum order quantity is 500 pieces and mixed orders are available; the allocation between models should be confirmed in the quotation. Samples are charged, with sample freight refunded after an order is placed. Typical lead time is 15–45 days, subject to the confirmed order.
Use our quotation checklist: https://www.nbtorchmark.com/posts/flaring-tool-rfq-specification-checklistFor larger sizes, see the separate CT-203 range: https://www.nbtorchmark.com/products/ct-203a-ct-203m-45-degree-flaring-tools
Further reference
For general background on copper tube, consult the Copper Development Association’s Copper Tube Handbook: https://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdfThis independent reference is not a certification of our tools. Model specifications above come from Ningbo Torchmark HVAC Tools Catalogue 2026, page 5.
Request the correct sample or quotation
Contact Amy: amy@longrunhardware.com | WhatsApp +86 158 6745 7689: https://wa.me/8615867457689Include the exact tube size and intended fitting in your message.
Author: Alisa Xu | Product Manager | 0086-13429254575
LinkedIn: https://www.linkedin.com/in/alisasourcing/
