Nozzle size
Nozzle size 2.5: orifice diameter and flow by pressure
A size 2.5 pressure washer nozzle: its 0.039 in orifice, 2.17 GPM at 3,000 PSI on General Pump's chart, and its flow at 1,500 and 2,000 PSI by the formula.
Also listed as 2.5 nozzle, 025 nozzle, size 2.5 orifice
Short answer
A size 2.5 nozzle has a 0.039 in equivalent orifice and flows 2.17 GPM at 3,000 PSI on General Pump's chart. By the formula Cat Pumps and General Pump publish, it flows about 1.53 GPM at 1,500 PSI and 1.77 GPM at 2,000 PSI (calculated), so it sits at the lower-flow end of the common sizes. No maker part in the sources read is sold as size 2.5. Work out your own machine's size from its rated PSI and GPM with nozzle size for your machine.
Key facts
- Orifice diameter
- 0.039 in (General Pump chart equivalent orifice diameter)[1]
- Flow at common pressures
- 2.17 GPM at 3,000 PSI (General Pump chart). Calculated with the formula Cat Pumps and General Pump publish: about 1.53 GPM at 1,500 PSI, 1.77 GPM at 2,000 PSI and 2.5 GPM at 4,000 PSI[1][2]Calculated values are reference math, not the measured output of any machine.
- Parts made in this size
- Not confirmedNo maker part in the sources read is stated as size 2.5.
- Machines makers pair it with
- Not confirmedNo maker in the sources read pairs size 2.5 with a named machine.
- Spray angle
- Separate from size: Cat Pumps says spray angle does not affect nozzle flow, so a 2.5 flows the same at 0 or 40 degrees[2][3]
- Wear
- Cat Pumps says worn nozzles are the most frequent cause of low pressure; replace a worn nozzle with the proper size, and never adjust the pressure regulating valve to make up for it[4]
- Not confirmed
- Not confirmedMaker parts sold as size 2.5, any maker pairing with a named machine, and wear rates.
Watch out for
- A size number is the flow in GPM at 4,000 PSI; at a lower pressure the same nozzle flows less, so read the flow at your machine's rated pressure.
- Calculated flows come from the published formula, not from a test of any machine.
- Color does not tell you the size: Generac's and Westinghouse's color codes mark the spray angle, not the flow size.
Questions
How much water does a size 2.5 nozzle flow?
General Pump's chart gives 2.17 GPM at 3,000 PSI. By the formula Cat Pumps and General Pump publish, it flows about 1.77 GPM at 2,000 PSI and 1.53 GPM at 1,500 PSI (calculated).[1][2]
What is the orifice diameter of a size 2.5 nozzle?
General Pump's chart lists size 2.5 at an equivalent orifice diameter of 0.039 in.[1]
Does a 2.5 nozzle's spray angle change its flow?
No. Cat Pumps says spray angle does not affect nozzle flow; the flow depends on the nozzle size and the pressure. See nozzle colors and spray angles.[2]