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Copper Tube Types: L, M, K and DWV for Plumbing and HVAC
Copper tube comes in four wall-thickness grades — Type K, L, M and DWV — and choosing the right one for your application is not a matter of “thicker is better.” Each type is optimized for a different pressure range and use case. This guide explains the differences so you can specify the correct tube without over-paying or under-designing.
The Four Types at a Glance
Type K has the thickest wall and is used for underground service and main water lines, where external damage and high pressure are concerns. Type L is the standard for residential water supply, the most commonly used copper tube in homes. Type M has a thinner wall and is used in residential heating and low-pressure water systems, where code allows. DWV (Drain-Waste-Vent) is the thinnest, for non-pressure drainage and vent lines. Se vores C12200 kobberrør.
| Type | Væg (1/2″) | Trykklassificering | Typisk brug |
|---|---|---|---|
| Type K | 0.049″ | Meget høj | Underground, main service |
| Type L | 0.040″ | Høj | Residential water supply |
| Type M | 0.028″ | Moderat | Residential heating, water |
| DWV | 0.025″ | Non-pressure | Drain, waste, vent |
Hard vs Soft Temper
Copper tube is also available in hard (rigid) and soft (udglødet) temperament. Hard tube is sold in 20-foot straight lengths and used with soldered or brazed fittings in open runs. Soft tube comes in coils and bends easily around corners without fittings, ideal for tight spaces and refrigerant lines. For HVAC refrigerant lines, soft Type L or ACR (Air Conditioning & Refrigeration) tube is the standard, with a 1/8 inch larger inside diameter than plumbing tube of the same nominal size.
Buying Advice
Check local code before specifying Type M — some jurisdictions require Type L for water supply. For underground burial, always use Type K, because the thinner wall of L or M can corrode or dent in soil. For refrigeration, use ACR tube specifically, not plumbing tube, because ACR is charged with nitrogen and capped to keep moisture out. Always confirm the wall thickness on the mill certificate, because “Type L” from different suppliers can vary slightly.
