Stihl SG 20 Backpack Sprayer Nozzles (Fit Guide)
The right nozzle for an STIHL SG 20 must match the sprayer’s installed holder, seal, and lance, as well as the product label and target. Check the actual connection instead of guessing from the sprayer model. The SG 20 holds 18 L and is rated to 6 bar maximum. Test with clean water, then calibrate using your fitted nozzle.
Start with the family-safe setup
A sprayer that leaks or delivers the wrong pattern can put product where it does not belong. If you share yard work with family, keep children and pets away while you mix, test, spray, and clean the SG 20. The product label sets the rules for protective gear, application, and re-entry.
The SG 20 is a manually pumped pesticide sprayer, not a powered tool. Its nominal tank capacity is 18 L, and its maximum operating pressure is 6 bar. Those figures describe the sprayer, not the output of every nozzle. Nozzle flow and droplet size vary with the nozzle, pressure, and operating conditions.
When I help identify a nozzle, I begin at the lance, not with a product listing. Two nozzles that look alike may not share the same connection or seal. First step: check the sprayer’s model-specific parts information and inspect the nozzle holder fitted to your machine.
Check nozzle fit before ordering
Fit means more than whether a nozzle can be turned onto the lance. The nozzle must match the installed holder or adapter, seat against the correct seal, and stay secure under pressure. STIHL parts and connections can differ by market or lance configuration, so verify the actual setup before buying.
Check these points:
- Model and lance: Confirm the SG 20 version and identify the lance and nozzle holder. Use the model-specific parts list or ask a STIHL dealer to confirm the correct part.
- Connection: Compare the replacement nozzle with the installed holder. Do not guess thread size from “SG 20” or rely on a “universal” label.
- Seal: Look for the required seal or washer and check it for cracks, flattening, or loss. A nozzle that lacks its proper seal may leak.
- Condition: Check the holder and threads for damage, corrosion, or residue. Do not force a part that binds or sits crooked.
| What to verify | What to do | Why it matters |
|---|---|---|
| Holder and connection | Match the part to the actual lance or model parts list | Prevents an incompatible or loose fit |
| Seal | Use the correct, intact seal | Helps prevent leaks |
| Nozzle pattern | Choose for the label-approved target | Affects where spray lands |
| Pressure and output | Use the nozzle chart, then test | Flow depends on the fitted nozzle and conditions |
If the parts list is unclear, take the lance or clear photos of its holder and seal to a dealer. Avoid ordering by appearance alone. Next step: confirm fit and seal before choosing a spray pattern.
Choose the pattern for the labeled job
A spray pattern is the shape and spread of liquid leaving the nozzle. A flat-fan nozzle forms a flattened band suited to directed, relatively even surface or band application. A cone-pattern nozzle spreads spray over a broader area and may suit foliage coverage when the product label allows it.
| Pattern or setup | Typical purpose | Check before use |
|---|---|---|
| Flat fan | Directed bands or surface treatment | Confirm the label allows that target and method |
| Cone pattern | Broader foliage coverage | Check label directions and drift risk |
| Unknown or worn pattern | No reliable application choice | Clean, inspect, or replace before spraying |
Pattern alone does not prove a nozzle is right for a chemical or task. The label controls permitted targets, application method, dose, and conditions. A broader pattern is not automatically better: wind, nearby plants, and the nozzle’s output all affect where product goes.
No single flow rate or droplet size applies to every SG 20. Check the nozzle maker’s chart for the fitted nozzle and the relevant operating pressure. If you cannot identify the nozzle or find its chart, do not assume an output value. Choose by label, then verify the actual spray with water.
Fit and test the nozzle safely
Depressurizing means releasing pressure from the sprayer as directed by its manual before opening or changing parts. Do this before removing the nozzle. A pressurized lance can release pesticide if a connection loosens, so keep the nozzle pointed away from people and wear the protective equipment required by the product label.
- Read first. Confirm the product, target, approved application method, dose, and required personal protective equipment (PPE) on the label. Check the safety data sheet (SDS) for additional hazard information.
- Inspect. Check the tank, hose, lance, lever, nozzle, filters, seals, and pressure-relief parts. Do not use damaged or leaking equipment.
- Use clean water. Fill enough for a controlled test. Pressurize and look for leaks before adding pesticide.
- Fit the nozzle. Depressurize, install the correct holder and seal, and tighten carefully. Stop if the threads resist; do not force them or use tape to make mismatched parts fit.
- Test the pattern. Pressurize with clean water and spray toward a safe test surface. Look for an even pattern, secure connections, and any leak or blockage.
Before spraying product, consider wind, nearby people and animals, water, sensitive plants, and site restrictions. Keep spray directed at the target and within label-approved conditions. If there is a leak, stop, depressurize, and repair it before use.
Calibrate the fitted nozzle
Calibration is a check of how much liquid your sprayer applies over a measured time or area. It matters because output depends on the installed nozzle and operating conditions, including pressure and pumping consistency. Calibrating the actual setup is more reliable than copying a generic SG 20 flow figure.
Use clean water and follow the product label’s directions:
- Keep the same nozzle, pumping rhythm, and walking speed you plan to use.
- For a timed check, spray into a measuring container for a set time and record the volume. Repeat the test to see whether results are consistent.
- For an area check, mark a known area and apply water as you would during the job. Record the amount used and the time taken.
- Compare your result with the label’s required application rate. Adjust only in ways the label permits, such as changing pace or using a suitable nozzle.
Do not raise pressure above the SG 20’s 6 bar maximum. A changed pumping rate can change delivery, so keep your method steady. If the output or coverage does not match the product directions, stop and check the nozzle chart, pattern, and technique before using pesticide. Write down the nozzle and test result so you can repeat a reliable setup.
Field fit scenarios: solve the mismatch
These examples show common fitting decisions, not specific STIHL part numbers or a claim that one nozzle fits every SG 20. In each case, verify the holder, seal, and product label before use. The point is to diagnose the setup rather than force a nozzle that seems close.
| Situation | Check | Safe next move |
|---|---|---|
| Replacement nozzle will not start smoothly | Compare its connection with the installed holder | Stop; verify the correct part through the parts list or dealer |
| Nozzle fits but liquid leaks at the joint | Inspect for the required seal and damage | Depressurize; fit the correct intact seal or replace damaged parts |
| Spray looks uneven after storage | Check for residue, a blocked screen, or nozzle wear | Depressurize, clean as directed, and test with water |
| Broad spray drifts toward nearby plants | Check wind, target, label method, and pattern | Stop until conditions and setup meet label directions |
When a nozzle connection is uncertain, I treat the parts list or dealer confirmation as the deciding check. A forced fit may damage threads or fail under pressure. A leak is not a calibration issue; it is a reason to stop, release pressure, and correct the connection. Do not spray until the fit is secure and the pattern is suitable.
Clean, troubleshoot, and store the nozzle
Nozzle maintenance means removing residue without changing the opening that meters the spray. A worn, damaged, or blocked nozzle can alter the pattern and output, which may lead to uneven treatment. Clean only after depressurizing, and use methods compatible with the sprayer materials and product label.
For a blockage, remove the nozzle as directed by the manual and rinse it. Use a soft brush or another approved cleaning method. Never clear it with wire or a drill bit; those can enlarge the opening. Never blow through a nozzle by mouth, which risks exposure.
Keep screens and filters clean. Avoid solvents or cleaners unless the manual and product label say they are suitable. Replace a nozzle that is cracked, corroded, worn, or still sprays unevenly after cleaning. Replace damaged seals too. A changed pattern or output can affect application.
After use, rinse and flush the sprayer and nozzle as the product label directs. Manage rinse water, or rinsate, as directed; do not discharge it into drains, waterways, or unapproved areas. Store the sprayer clean, dry, depressurized, and protected from freezing and chemical residue. Check the nozzle fit and seals before the next season. A clean, intact nozzle is easier to verify at the next start.
Frequently asked questions
These answers cover the most common fit, pattern, and care questions for an SG 20 nozzle. The actual connection and output depend on the installed lance, holder, nozzle, and operating conditions. Use the model-specific parts information and product label to confirm the right setup.
Does every nozzle advertised as universal fit the SG 20?
No. Confirm the connection and seal against the installed holder or model-specific parts information. Do not assume a universal nozzle will fit or seal.
What is the SG 20’s maximum pressure?
The maximum operating pressure is 6 bar. Do not exceed the sprayer’s rating.
What is the SG 20 tank capacity?
Its nominal tank capacity is 18 L. Follow the manual for correct filling and operation.
Which nozzle pattern should I use?
Use a flat fan for directed bands or surfaces, or a cone pattern for broader foliage coverage, only when the product label permits that application.
What flow rate should an SG 20 nozzle deliver?
There is no single flow rate for all SG 20 setups. Check the nozzle manufacturer’s chart and calibrate the fitted nozzle under consistent conditions.
Can I change the nozzle while the sprayer is pressurized?
No. Depressurize the sprayer as the manual directs before changing or cleaning a nozzle.
Can I use wire to clear a blocked nozzle?
No. Wire, drill bits, and similar hard tools can enlarge the opening. Rinse and clean it using an approved method.
What should I do if the nozzle leaks?
Stop spraying, point the lance away from people, and depressurize. Inspect the fit, seal, and parts; do not resume until the leak is fixed.
The reliable fit check
A dependable setup starts with the installed holder, correct seal, and verified connection. Then choose a pattern allowed by the product label, test with clean water, and calibrate the actual nozzle. Keep pressure within 6 bar, clean without damaging the opening, and store the sprayer clean and depressurized.
If fit or part identity remains uncertain, pause and confirm it through the SG 20 parts information or a STIHL dealer. That check is safer than forcing a connection or guessing at output.
(This article was written by one of our staff writers, Harrison Croft. Visit our Meet the Team page.)
