Fertigation Machine Spares: Keeping Your Dosing System Running All Season

Fertigation Machine Spares: Keeping Your Dosing System Running All Season

Introduction

A fertigation machine is one of the most important and complex pieces of equipment in a professional growing operation. When it is working correctly, it delivers precise, consistent nutrition to your crop day after day. When a component fails — a worn dosing valve, a blocked venturi, a drifting pH sensor — the consequences can range from inaccurate feeding to complete system shutdown at a critical point in the growing season.

Having the right spares on hand, and knowing how to identify which part needs replacing, is essential for minimising downtime and protecting your crop. IrriSmart stocks a comprehensive range of fertigation system spares covering dosing channels, valves, sensors, rotometers, venturis, and control system components.

This guide covers the full spares range, explains what each component does, and helps you identify the right part for your system.

Dosing Channel Spares

The dosing channel is the heart of a fertigation machine — it is the assembly that draws fertiliser concentrate from the stock tank, meters it through a rotometer, and injects it into the irrigation water via a dosing valve. Each channel typically handles one fertiliser concentrate or acid.

Dosing channels consist of a series of connected components, and wear or blockage in any one of them can affect dosing accuracy or cause the channel to stop functioning. IrriSmart stocks the full range of dosing channel spares:

Dosing Channel Connectors and Fittings

The connectors between components in the dosing channel — from the hose nozzle end connector through to the needle valve and dosing valve — are subject to chemical attack and mechanical wear over time. Key connectors available include:

  • Hose nozzle end connectors
  • Connectors from hose nozzle to Rotameter 170 and 185
  • Connectors from Rotameter to needle valve
  • Connectors from needle valve to dosing valve (S12 and Baccara)
  • O-ring and washer sets for dosing channels
  • Union O-rings for 16mm unions
  • Rubber washers for 16mm hose nozzles

Needle Valves

Needle valves provide fine flow adjustment within the dosing channel, allowing the operator to set the flow rate through each channel precisely. Available in low flow and high flow versions to suit different channel capacities, plus the FIP RPRV 1/2 inch FPM needle valve for high-flow applications up to 1,000 L/hr.

Line Check Valves

Check valves prevent backflow within the dosing channel, protecting the stock tank from contamination and preventing fertiliser from siphoning back into the water supply. Available in multiple configurations:

  • 3/4 inch x 1 inch EPDM
  • 3/4 inch x 3/4 inch EPDM and Viton
  • 3/4 inch x 1/2 inch male Viton

Viton seals offer superior chemical resistance for use with aggressive acids and concentrated fertilisers; EPDM is suitable for standard fertiliser solutions.

Browse all dosing channel spares in our Fertigation System Spares collection.

Spare Rotometers

The rotometer (flow meter) in each dosing channel provides a visual indication of the fertiliser flow rate and allows the operator to set and verify the dosing rate. Rotometers can become blocked by crystallised fertiliser deposits or damaged by chemical attack over time.

IrriSmart stocks Stubbe DFM rotometers in four flow ranges to cover the standard dosing channel configurations used in professional fertigation machines:

  • DFM170 — 5 to 50 L/hr — typically used for acid dosing channels
  • DFM170 — 15 to 150 L/hr — for medium-flow acid channels on larger systems
  • DFM170 — 40 to 400 L/hr — standard fertiliser channel on most professional machines
  • DFM185 — 60 to 600 L/hr — for higher-capacity fertiliser channels on larger systems

Important: Standard dosing channels typically use 600 L/hr fertiliser and 50 L/hr acid rotometers. Older systems may use 400 L/hr fertiliser channels. Larger systems may use 1,000 L/hr fertiliser and 150 L/hr acid channels. Always check your existing rotometer range before ordering a replacement.

View spare rotometers

Dosing Valves

The dosing valve is the component that injects the metered fertiliser concentrate into the irrigation water stream. It is a solenoid-operated valve that opens and closes rapidly to deliver precise doses. Dosing valves are subject to wear from chemical attack and mechanical cycling, and are one of the most commonly replaced components in a fertigation machine.

IrriSmart stocks two dosing valve types to cover the most common fertigation machine brands:

  • FIP S12 Dosing Valve — 24VAC, Viton seals — compatible with Munters, Rivulis, Galcon, and Neatfim controllers and dosing systems. Viton seals provide excellent resistance to acids and concentrated fertilisers.
  • Baccara Dosing Valve — 1/2 inch, EPDM, 24VAC — compatible with Munters, Rivulis, Galcon, Neatfim, and Priva systems. A versatile option for a wider range of machine brands.
  • Connection cable for FIP S22/S12 24VAC valves — replacement wiring connector for S12 and S22 dosing valves.

View dosing valves and connectors

FSP Venturis

The venturi in a fertigation machine creates the suction that draws fertiliser concentrate from the stock tank into the dosing channel. Venturis can become blocked by crystallised fertiliser or damaged by chemical attack, particularly when used with aggressive acids.

IrriSmart stocks FSP venturis in PVC and PVDF materials across a range of flow capacities:

  • FSP Venturi PVC N600 — single and dual configurations for 600 L/hr channels
  • FSP Venturi PVC N1000 — single and dual configurations for 1,000 L/hr channels
  • FSP Venturi PVDF M50 — PVDF construction for superior chemical resistance, suitable for aggressive acids and high-concentration fertilisers

PVDF (polyvinylidene fluoride) offers significantly better chemical resistance than PVC and is recommended for acid dosing channels or where highly concentrated fertilisers are used.

View FSP venturis

Dosing Channel Expansions

If your fertigation machine needs additional dosing capacity — for example, to add a new fertiliser concentrate or an acid channel — complete dosing channel expansion assemblies are available. These are pre-assembled channel units that can be added to compatible fertigation machines:

  • Dual 400 L/hr channel — Baccara 50Hz, EPDM, PVC600
  • Single 600 L/hr channel — S12, EPDM, PVC600
  • Dual 1,000 L/hr channel — S22, EPDM, PVC1000
  • Single 50 L/hr channel — S12, Viton, PVDF50 (for acid dosing)

View dosing channel expansions

EC and pH Sensors

EC and pH sensors are the eyes of your fertigation machine — they measure the actual nutrient concentration and acidity of the irrigation water and feed this data back to the controller for closed-loop control. Sensors drift over time and require regular calibration; they also have a finite service life and will eventually need replacement.

pH Sensor

The JUMO 12mm glass pH sensor with BNC connection is a high-quality laboratory-grade sensor suitable for continuous immersion in irrigation water. Glass pH sensors provide accurate, stable readings but require regular calibration with buffer solutions and careful handling to avoid damage to the glass electrode.

EC Sensor

The JUMO 12mm EC sensor with temperature compensation (PT100) provides accurate EC readings corrected for water temperature — essential for reliable EC control, as EC readings vary significantly with temperature. The PT100 temperature sensor is integrated into the same probe body for convenience.

EC/pH Union Adaptor Set

The union adaptor set for JUMO sensors provides the correct fittings to install JUMO EC and pH sensors into the fertigation machine's sensor housing, ensuring a watertight, chemically resistant connection.

View EC and pH sensors

EC/pH Transmitter

The EC/pH transmitter (24V wall mount monitor) is the control unit that reads the sensor signals, displays EC and pH values, and outputs control signals to the fertigation machine. If your transmitter develops a fault — displaying erratic readings, failing to respond to sensor inputs, or losing calibration — replacement may be required.

View the EC/pH transmitter

Buffer Solutions for Sensor Calibration

Regular calibration of pH and EC sensors is essential for accurate fertigation control. Sensors drift over time, and a sensor that is out of calibration will cause the fertigation machine to dose incorrectly — potentially causing nutrient deficiencies or toxicities in the crop.

IrriSmart stocks Milwaukee calibration sachets for both pH and EC calibration:

  • pH 4.01 buffer solution — 20ml sachet — for calibrating the acid end of the pH scale
  • pH 7.01 buffer solution — 20ml sachet — for calibrating the neutral point of the pH scale
  • 1.413 mS/cm EC calibration solution — 20ml sachet — for calibrating EC sensors

Single-use sachets ensure that the calibration solution is always fresh and uncontaminated — a critical factor for accurate calibration. We recommend calibrating pH sensors with both pH 4.01 and pH 7.01 solutions (two-point calibration) for maximum accuracy across the working range.

View buffer solutions

Spare and Expansion Cards

For operations using NMC (Nutrient Management Controller) systems, IrriSmart stocks a comprehensive range of NMC spare and expansion cards covering:

  • Keyboard cards for LED/LCD displays
  • Input/output bus cards
  • Power supply cards (230V)
  • 24V output additional cards
  • Dry contact output cards
  • Digital input cards
  • Analog input cards
  • RS232 communication cards
  • CPU cards

These cards allow NMC systems to be expanded with additional inputs and outputs as growing operations scale up, or replaced when individual cards develop faults.

Environmental Sensors

For operations using NMC climate and environmental monitoring systems, IrriSmart also stocks a range of environmental sensors:

  • Temperature and humidity measuring box — for monitoring greenhouse climate conditions
  • Humidity sensor replacement tip — for servicing existing humidity sensors
  • Pyranometer (solar radiation sensor) — for measuring light levels to support ET-based irrigation scheduling
  • Wind speed and direction sensor — for outdoor climate monitoring

View all environmental sensors and spares

Keeping a Spares Kit

The most effective way to minimise fertigation system downtime is to keep a small stock of the most commonly replaced components on site. We recommend the following as a minimum spares kit for any professional fertigation installation:

  • One set of O-rings and washers for each dosing channel
  • One spare dosing valve of each type fitted to your machine
  • One spare rotometer of each flow range used in your system
  • A stock of pH 4.01, pH 7.01, and EC 1.413 calibration sachets
  • One spare pH sensor (glass sensors are fragile and can break unexpectedly)
  • Spare needle valves and check valves for each channel type

The cost of holding these spares is trivial compared to the cost of a day's crop stress or lost production while waiting for a part to be delivered.

Conclusion

IrriSmart's Fertigation System Spares range covers the full spectrum of components needed to maintain and repair professional fertigation machines, from individual O-rings and calibration sachets to complete dosing channel assemblies and control system cards.

Browse the complete Fertigation System Spares collection online, or contact our team if you need help identifying the right part for your machine. With 20+ years of irrigation experience, we can help you diagnose faults and source the correct replacement components quickly.

Back to blog