27
Metering Unit
The flow rate can be infinitely varied by means of the
metering knob (1) on the nozzle (2). Metering knob
position "1" is the minimum flow rate and "6" the
maximum.
The required number on the metering knob (1) must be
lined up with the molded lug (3).
The numbers on the metering knob (1) represent the
following spray rates:
1.
Spray rate without booster pump
Metering
Spray rate
SR 320, SR 400
knob
without baffle
with baffle
position
I/min
(US gal/h) I/min
(US gal/h)
1
0.13
(2.0)
0.14
(2.3)
2
0.61
(9.5)
0.71
(11.1)
3
1.27
(20.2)
1.33
(21.0)
4
1.92
(30.5)
2.09
(33.2)
5
2.49
(39.2)
2.67
(42.4)
6
2.78
(43.9)
3.03
(47.5)
2.
Spray rate with booster pump
(metering knob position 6)
Spray rate I/min
(US gal/h)
Metering
SR 320
SR 400
nozzle
1
0.53
(8.3)
0.57
(9.1)
2
1.42
(22.5)
1.54 (24.5)
3
2.44
(38.8)
2.32
(36.8)
Checking the metering unit (without booster pump)
- Place the unit on the ground.
- Fill the container with water up to the 10 liter (2 gal)
mark.
- Set metering knob (1) to position 6.
- Start the unit (baffle removed).
- Hold the spray tube horizontally, run the engine at full
throttle, spray the contents of the container down to the
5 liter (1 gal) mark and make a note of the time taken.
The SR 320 and SR 400 should spray 5 liters (1 gal) fluid
within 80 to 100 seconds.
If the time required is longer, check the metering unit for
contamination and clean it if necessary. Also check the
carburetor setting and correct it as necessary.
If there is no noticeable improvement, please contact your
STIHL dealer for assistance.
Nozzle with metering unit
