Dosing accessories — injection nozzle, foot valve and level switch
Short answer: A dosing pump on its own is not a dosing system. The foot valve keeps the suction line primed, the injection nozzle stops line water flowing back, and the level switch stops the pump when the tank empties. Missing any one of these causes a recurring problem.
Together they cost about ₹3,000 and prevent most of the dosing failures we see.
The foot valve
Sits at the bottom of the suction line inside the chemical tank. It is a non-return valve with a strainer.
What it does
- Holds chemical in the suction line so the pump stays primed
- Strains out any particles that would jam the pump valves
- Keeps the suction line full between strokes
Without it
Chemical drains back into the tank between strokes and the pump has to re-prime each time. In practice the pump runs but doses very little or nothing at all — and from outside it looks like it is working.
The injection nozzle
Fits where the chemical enters the main water line. It is also a non-return valve.
What it does
- Stops line water flowing back into the chemical line
- Injects the chemical into the middle of the flow, where it mixes properly
- Provides back pressure so the pump doses accurately
Without it
- Line water pushes back into the chemical line and the pump cannot dose against it
- Chemical dribbles down the pipe wall instead of mixing
- Line water can reach the chemical tank
Available as the injection nozzle 1/2 NPT with adaptor at ₹761.
The level switch
Sits in the chemical tank and signals when the level drops too low.
What it does
- Stops the pump so it does not run dry, which damages it
- Can trigger an alarm, or stop the plant entirely
- Ensures somebody finds out that the tank is empty
Full accessory list
| Item | Function | Price |
|---|---|---|
| Injection nozzle 1/2 NPT | Injection point, non-return | ₹761 |
| Level switch | Stops pump when tank empties | ₹1,050 |
| Dosing vessel 15 L | Chemical tank, LLDPE | ₹3,465 |
| Dosing vessel 10 L | Smaller tank | ₹2,835 |
See our dosing accessories range.
Sizing the dosing tank
The tank should hold enough for a sensible refill interval, but not so much that solution sits for weeks:
- Antiscalant solution — do not keep more than 15 to 20 days, bacteria can develop
- SMBS solution — 7 to 10 days maximum, it loses strength
So size the tank for roughly a week to ten days of consumption. A very large tank is not an advantage.
Installation points
- Mount the tank above the pump where possible — flooded suction primes far more reliably
- Keep the suction line short and free of high points where air can collect
- Foot valve off the tank bottom — an inch or two up, so it does not draw sediment
- Injection nozzle into the flow, not flush with the pipe wall
- Keep the tank covered — dust and insects otherwise get in
- Label the tank clearly with the chemical name
Diagnosing dosing failures
| Symptom | Check |
|---|---|
| Pump runs, tank level not falling | Foot valve, air lock in suction line |
| Pump will not prime | Foot valve, suction line height |
| Water in the chemical tank | Injection nozzle failed |
| Dose inconsistent | Back pressure, worn valves |
| Pump damaged | Ran dry — fit a level switch |
| Chemical crystallising at injection point | Nozzle blocked, clean or replace |
Full troubleshooting is in our priming guide.
Separate systems for separate chemicals
The correct injection order is covered in our pre-treatment design guide.
Complete your dosing system
Send your pump model and chemical, and we will supply the nozzle, foot valve, level switch and tank as a set.
💬 WhatsApp par poochhein 📞 9910646957Frequently asked questions
What does the foot valve do?
It sits at the bottom of the suction line and holds chemical in the line so the pump stays primed, while also straining out particles. Without it the chemical drains back between strokes and the pump doses very little despite appearing to run normally.
Why is an injection nozzle needed?
It stops line water flowing back into the chemical line, injects the chemical into the middle of the flow where it mixes properly, and provides back pressure so the pump doses accurately.
What does a level switch protect against?
It stops the pump when the tank empties, which prevents the pump running dry and being damaged, and more importantly ensures somebody finds out the tank is empty rather than the plant running for weeks without chemical.
How large should a dosing tank be?
Enough for about a week to ten days of consumption. Antiscalant solution should not be kept more than fifteen to twenty days and SMBS not more than seven to ten, so a very large tank is not an advantage.
Can two chemicals share a dosing tank?
No. Antiscalant and SMBS need separate tanks, separate pumps and separate injection points at different positions in the line. Mixing them wastes both and can produce deposits.