What DZR Means for C35330 Hollow Bar
DZR stands for dezincification-resistant. C35330 hollow bar is a leaded brass micro-alloyed with arsenic at approximately 0.02-0.15% and produced with a controlled phase structure. In aggressive waters, meaning soft, acidic or high-chloride supplies, ordinary high-zinc brass loses zinc by selective leaching. The attacked zone turns porous and copper-rich, and the component eventually fails by leaking or by cracking under normal system pressure. The arsenic addition and the structural control suppress that leaching mechanism, so the alloy keeps its wall thickness and its pressure integrity over a long service life.
Compliance with the DZR claim is not a marketing statement; it is verified by a dezincification depth test to ISO 6509, with a limit typically at or below 200 micrometres, corresponding to class Y in EN 12164 and EN 12165. Buyers should ask for that test result rather than accept the letters DZR alone.
Chemistry of CuZn37Pb2
| Element | Min-Max (%) | Nominal (%) |
|---|---|---|
| Cu | 60.0-63.0 | 61.5 |
| Fe | 0.15 max | - |
| Pb | 1.5-2.5 | 2.0 |
| Zn | Remainder | 36.5 |
| As | Micro-alloying addition | 0.02-0.15 |
The lead addition at 1.5-2.5% is what makes the grade practical on automatic screw machines: it lubricates the chip and controls its breakage, so couplings, nuts and valve internals can be produced at high rates with consistent surface finish.
Equivalent Specifications
| System | Designation |
|---|---|
| ISO | CuZn37Pb2 |
| European | CuZn37Pb2 |
| BS | CZ119 |
| DZR verification | ISO 6509 depth test, typically 200 micrometres max, class Y per EN 12164 / EN 12165 |
Physical and Electrical Properties
| Property | Value |
|---|---|
| Melting point, liquidus | 1670 F |
| Melting point, solidus | 1630 F |
| Specific gravity | 8.470 |
| Density | 0.306 lb/in3 at 68 F |
| Coefficient of thermal expansion | 11.30 x 10-6 per F, 68-572 F |
| Electrical conductivity | 26 %IACS at 68 F |
| Electrical resistivity | 39.9 ohm-cmil/ft at 68 F |
| Modulus of elasticity in tension | 15000 ksi |
| Modulus of rigidity | 5600 ksi |
| Thermal conductivity | 67 BTU in/hr.ft2.F at 68 F |
The conductivity figures place the alloy in the mid range for brass, which is appropriate for a pressure-retaining water component rather than a current-carrying part. The relatively high modulus and the narrow melting interval are the values a designer needs when sizing wall sections and checking brazing cycles.
Hollow Bar and Other Stock Sizes
Hollow rods: minimum bore 20 mm, maximum outside diameter 100 mm
Round rods: 6 mm to 130 mm
Hexagon: 5 mm to 60 mm
Square: 4 mm to 60 mm
Flat: 5 mm minimum thickness, maximum width 120 mm
Wire: 1 mm to 8 mm
Profiles and sections: produced to customer drawing
Billets: up to 200 mm
Ingots: as per specification
Hollow bar is the efficient starting point for valve bodies and fittings because the bore already exists. Drilling a solid rod removes metal that has already been paid for, adds cycle time and consumes tool life, so a stock near-net bore is usually the lower-cost route for parts below roughly 100 mm outside diameter.
Applications in Water Systems
DZR C35330 hollow bar is used for potable-water fittings and connectors qualified to EN 12164 or AS 4020, for ball, gate and check valve bodies in water systems, for water meters, stopcocks and heating circuit components, and for sanitary and radiator valves where dezincification would otherwise end the service life early. Machined hardware such as hinges, drawer pulls, key blanks, rivets, screws, valve stems, flare fittings and couplings also uses the grade, because the same lead addition that speeds machining also supports thread rolling and knurling.
Where a system combines soft or high-chloride water with a long design life, specifying DZR chemistry from the start is cheaper than replacing ordinary brass fittings after the first failure. The relevant check is the ISO 6509 depth result on the actual heat, not the appearance of the finished part.
Frequently Asked Questions
Q: What does DZR mean in brass hollow bar?
DZR means dezincification-resistant. The alloy is micro-alloyed with arsenic so that zinc is not selectively leached out of the surface in soft, acidic or high-chloride water.
Q: How is dezincification resistance verified?
By a depth test to ISO 6509, with a limit typically at or below 200 micrometres, which corresponds to class Y in EN 12164 and EN 12165.
Q: What is the chemical composition of CuZn37Pb2?
Copper 60.0-63.0%, lead 1.5-2.5%, iron 0.15% maximum and zinc as the remainder, with nominals of 61.5% Cu, 2.0% Pb and 36.5% Zn.
Q: Which hollow bar sizes are stocked?
Hollow rods run from a 20 mm minimum bore up to 100 mm maximum outside diameter, alongside round rods of 6-130 mm, hexagon 5-60 mm and square 4-60 mm.
Q: Can C35330 be used for potable water?
Yes. The grade is used for potable-water fittings and valve bodies qualified to EN 12164 or AS 4020, which is the reason the DZR behaviour matters in the first place.
Q: How does the alloy behave on automatic screw machines?
The 1.5-2.5% lead addition lubricates and breaks the chip, allowing high production rates on nuts, couplings, valve stems and similar parts with a good as-machined finish.
