FORTIS FOAM
A dosing pump is a precision device that injects a measured amount of concentrate into the water stream, creating a working solution at the correct dilution ratio. In professional car washes, dosing pumps are the backbone of chemical management — they determine both cleaning quality and cost per wash.
Types of car wash dosing pumps
Venturi injectors
The simplest and cheapest option. A Venturi injector uses the pressure differential in the water line to draw concentrate through a suction tube — no electricity required. Cost: $50–$200.
Pros: No moving parts, no electricity, cheap, reliable Cons: Less precise, output varies with water pressure changes, limited to low-viscosity concentrates
Best for: Small self-service car washes, mobile detailing units
Peristaltic pumps
A motor-driven roller squeezes flexible tubing, pushing fluid forward in precise, measured doses. The fluid only contacts the tubing — never the pump mechanism — making peristaltic pumps ideal for corrosive chemicals. Cost: $200–$800.
Pros: Highly accurate (±1%), self-priming, easy tube replacement, chemical-resistant Cons: Tubing wears out (replace every 6–12 months), limited flow rate
Best for: Touchless car washes with 2–4 bays, where accuracy matters for products like Fortis Foam PRO (dilution range 1:100 to 1:200)
Diaphragm pumps
A flexible diaphragm moves back and forth, drawing in and expelling fluid. More robust than peristaltic pumps and capable of higher pressures and flow rates. Cost: $300–$1,500.
Pros: High pressure capability, handles viscous fluids, long service life Cons: More complex maintenance, pulsating flow may need dampening
Best for: High-volume tunnel washes, multi-product systems
Proportional dosing systems
The most advanced option. A flow meter measures water flow in real time, and a controller adjusts the concentrate injection rate proportionally. The dilution ratio stays constant regardless of water pressure fluctuations. Cost: $1,000–$5,000.
Pros: Constant ratio accuracy, automatic adjustment, reduced waste, data logging Cons: Expensive, requires electrical connection and calibration expertise
Best for: Professional multi-bay operations, tunnel washes, franchise operations with quality standards
How to select the right dosing pump
| Factor | Venturi | Peristaltic | Diaphragm | Proportional |
|---|---|---|---|---|
| Accuracy | ±15–20% | ±1–3% | ±3–5% | ±1% |
| Cost | $50–200 | $200–800 | $300–1,500 | $1,000–5,000 |
| Electricity required | No | Yes | Yes | Yes |
| Maintenance | Minimal | Tube replacement | Moderate | Professional |
| Best for | Budget/mobile | Small-medium | High-volume | Premium operations |
Sizing considerations
The pump must deliver enough concentrate to maintain the correct dilution at your water flow rate. Example calculation:
- Water flow: 12 liters/minute (typical touchless bay)
- Target dilution: 1:150 (Fortis Foam PRO summer setting)
- Required concentrate flow: 12 ÷ 150 = 0.08 liters/minute (80 ml/min)
If you run 4 bays simultaneously: 4 × 80 = 320 ml/min total concentrate flow.
Best diaphragm pump for tunnel car wash chemical injection
Tunnel washes run long hours at high flow, switch products every few seconds and use aggressive acids and alkaline presoaks. That rules out Venturi injectors and most peristaltic pumps for the main arches. A diaphragm metering pump is the standard choice. What to look for:
| Feature | Why it matters in a tunnel |
|---|---|
| PVDF or PTFE wetted parts, PTFE-faced diaphragm | Survives both low-pH wheel cleaners and high-pH presoaks |
| Motor-driven or stepper drive (rather than basic solenoid) | Smoother, more repeatable output at high duty cycles |
| Stroke-length and stroke-rate adjustment | Fine-tunes dose without changing the pump |
| 4–20 mA / pulse input | Lets the tunnel controller change dose per wash package |
| Capacity 20–30% above peak concentrate flow | Avoids running at 100% stroke, which shortens diaphragm life |
| Pulsation dampener + foot valve | Stable foam at the arch and no loss of prime between cars |
Rule of thumb: one pump per chemical per application point (presoak arch, wheel cleaner, foam arch, wax, drying agent). Feeding several arches from one pump makes the dilution drift whenever two arches run at once.
How touchless car washes meter chemicals at each wash stage
In an in-bay automatic or touchless tunnel, the controller fires a separate dosing channel for every stage of the program. Each channel has its own pump (or proportioner) and target ratio:
| Wash stage | Typical chemistry | Typical dilution | Pump type commonly used |
|---|---|---|---|
| Presoak 1 | Alkaline active foam | 1:100 – 1:200 | Diaphragm or proportional |
| Presoak 2 / wheels | Low-pH cleaner | 1:50 – 1:150 | Diaphragm (acid-resistant) |
| Foam / shampoo | Neutral shampoo, foam polish | 1:200 – 1:400 | Diaphragm or peristaltic |
| Rinse aid / sealant | Wax, sealant | 1:500 – 1:1,000 | Peristaltic (low flow, high accuracy) |
| Drying agent | Cationic drying aid | 1:500 – 1:1,000 | Peristaltic |
The controller opens the water solenoid for a stage, the pump on that channel injects concentrate at the set stroke, and the high-pressure pump delivers the working solution to the arch. Accuracy matters most on the first presoak — it does most of the cleaning and is where overdosing costs the most. See two-step washing with alkaline and acidic foams for how the presoak stages work together.
Foam dosing pumps for viscous concentrates
Thick foam concentrates and polishes can starve a Venturi injector and make cheap solenoid pumps lose prime. For viscous products choose a diaphragm pump with larger valve ports and spring-loaded valves, keep the suction line short and wide (8–10 mm ID), and warm the concentrate room above 10°C in winter — viscosity rises sharply in the cold and the dose drops with it.
How much does an automated dosing system cost for a self-serve car wash?
Upgrading a self-serve car wash from Venturi injectors to electric metering pumps typically costs:
| Scope | Typical cost |
|---|---|
| One peristaltic or solenoid diaphragm pump per product per bay | $200 – $800 per pump |
| 4-bay site, 3 products per bay (12 pumps) | $3,000 – $10,000 incl. installation |
| Central proportional dosing with flow meters and controller | $5,000 – $15,000 per site |
With typical overdosing of 15–20% on Venturi systems, a 4-bay self-serve site often recovers the upgrade cost within 12–24 months through lower chemical consumption — see the cost table below.
Calibration and verification
Calibrate your dosing pump at least monthly. Two methods:
Method 1: Volumetric test
- Disconnect concentrate line from the tank
- Place intake in a graduated container with a known volume (e.g., 500 ml)
- Run water for exactly 1 minute
- Measure concentrate consumed
- Calculate actual ratio: water flow ÷ concentrate consumed
Method 2: Refractometer
A refractometer measures the refractive index of the working solution, which correlates with concentration. Faster and more convenient for daily checks, but requires calibration against a known standard.
Target pH values for verification:
- Fortis Foam PRO at 1:100 → pH 12.0
- Fortis Foam PRO at 1:200 → pH 11.7
- Fortis Foam ECO at 1:100 → pH 8.5
- Fortis Foam ECO at 1:150 → pH 8.3
A simple pH meter ($30–$100) can serve as a quick dosing verification tool.
Common dosing problems and solutions
| Symptom | Likely cause | Fix |
|---|---|---|
| Weak wash results | Underdosing — worn tubing, clogged filter | Replace tubing, clean filter, recalibrate |
| Excessive foam, slow rinse | Overdosing — pump set too high | Reduce pump stroke, verify ratio |
| Inconsistent results | Air leak in suction line | Check all fittings, replace cracked tubing |
| Pump runs but no concentrate | Empty tank, blocked pickup tube | Refill tank, clear blockage |
| Chemical crystals in tubing | Concentrate dried in idle pump | Flush system with warm water weekly |
Impact on operating costs
Dosing accuracy directly impacts your bottom line. For a 4-bay touchless wash running 150 cars/day with Fortis Foam PRO:
| Dosing accuracy | Actual ratio | Concentrate/day | Monthly cost impact |
|---|---|---|---|
| Correct (1:150) | 1:150 | 12L | Baseline |
| 10% overdose | 1:136 | 13.2L | +€30/month |
| 20% overdose | 1:125 | 14.4L | +€60/month |
| 10% underdose | 1:165 | 10.9L | -€25/month (but poor wash!) |
A 20% overdose over a year costs €720 in wasted chemistry — more than the price of a quality peristaltic pump. Underdosing saves chemistry but costs you customers.
Maintenance schedule
| Task | Frequency |
|---|---|
| Visual inspection (leaks, tubing condition) | Daily |
| pH spot check of working solution | Weekly |
| Full calibration with volumetric test | Monthly |
| Tubing replacement (peristaltic pumps) | Every 6–12 months |
| Diaphragm/valve replacement | Every 12–24 months |
| Intake filter cleaning | Monthly |
Installation best practices
Proper installation prevents most dosing problems before they start:
- Mount the pump above the concentrate tank — this prevents siphoning when the pump is off and reduces the risk of air entering the suction line
- Keep suction lines short — maximum 2 meters between tank and pump. Longer lines increase priming time and risk air pockets
- Install a foot valve and strainer in the concentrate tank to prevent debris from reaching the pump and to maintain prime
- Use chemical-resistant tubing — PVC or PVDF for acidic products, polyethylene for alkaline foams. Standard rubber tubing degrades quickly with concentrated chemicals
- Add a pulsation dampener after diaphragm pumps to ensure smooth, consistent foam application at the nozzle
- Label everything — mark each pump with the product it doses, the target dilution ratio, and the last calibration date
Frequently asked questions
What is a dosing pump in a car wash?
A dosing pump (also called a metering pump or chemical injection pump) is a device that automatically injects a precise amount of concentrated car wash chemical — such as active foam, wax, or rinse aid — into the water stream. It ensures every vehicle receives the correct chemical concentration for consistent wash quality and predictable operating costs.
How long does a car wash dosing pump last?
With proper maintenance, a quality dosing pump lasts 5–10 years. Peristaltic pump tubing needs replacing every 6–12 months ($20–$50). Diaphragm pumps need diaphragm and valve replacements every 12–24 months ($50–$150). Venturi injectors with no moving parts can last 10+ years but may need periodic cleaning to remove mineral buildup.
How do I know if my dosing pump is working correctly?
Three quick checks: (1) Measure the pH of the working solution at the nozzle — it should match the expected value for your target dilution. (2) Perform a volumetric test — disconnect the concentrate line, pump into a graduated container for 60 seconds, and calculate the actual ratio. (3) Monitor your monthly concentrate consumption per vehicle — sudden changes indicate pump drift or failure.
Venturi injector or electric pump — which is better for a small car wash?
For a self-service wash with 1–2 bays and fewer than 50 cars per day, a Venturi injector is usually sufficient. It is cheap ($50–$200), requires no electricity, and has no moving parts to fail. However, its accuracy (±15–20%) is lower than electric pumps. If wash consistency matters — for example, when using premium products like Fortis Foam PRO with a narrow optimal dilution range — a peristaltic pump ($200–$800) is a better investment that typically pays for itself within a year through reduced chemical waste.
What diaphragm pump is best for chemical injection in a tunnel car wash?
Look for a motor-driven or stepper-motor diaphragm metering pump with PVDF or PTFE wetted parts, adjustable stroke and a 4–20 mA or pulse input so the tunnel controller can change the dose per wash package. Size it for 20–30% above your peak concentrate flow, add a pulsation dampener and a foot valve, and use one pump per chemical and arch rather than one pump feeding several products.
Incorrect dosing is one of the most frequent — and costliest — mistakes in car wash operations. Read our detailed guide on dosing mistakes to avoid and learn how to calculate foam consumption accurately.