IFM LDL100 Conductivity Sensor

Nome completo do modelo: LDL100 COND CONDUCTIVITY HYG G1/2

IFM hygienic two-electrode conductivity sensor with integrated transmitter (electrode + signal processing unit). No separate transmitter required. Supports IO-Link plus 4~20 mA analogue output. Widely used for CIP cleaning and phase interface detection in food & indústrias farmacêuticas.

✅ Core Measurement Specifications

Conductivity range: 100 ~ 15000 µS/cm, resolução 1 µS/cm

Medição de temperatura: -25 ~ +150 ℃, compensação de temperatura integrada

Conductivity accuracy: ±25 µS/cm within 10% de escala completa; Temperature accuracy: ＜±0.5 K at 20~50 ℃, ＜±1.5 K across full range

Tempo de resposta: <2 é (T09)

Desvio de temperatura: 0.2 %/K MW ±25 µS/cm

⚡ Electrical Parameters

Fornecer: DC 18~30 V, proteção contra polaridade reversa

Saída: 4~20 mA analogue (selectable for conductivity or temperature) + Link IO

Máx.. load for analogue output: 500 Oh

Power-on delay: 2 é

Conector: M12

Classe de proteção: IP69K (suitable for hygienic high-pressure washdown)

🛠 Mechanical & Materiais molhados

Process thread: G1/2 external tapered sealing thread

Wetted materials: 316L aço inoxidável (1.4404), ESPIAR; seal FKM; housing PEI

Wetted surface roughness: Ra ≤0.8 μm (hygienic finish)

Peso: 270.5 g

Installation note: O sensor carcaça metálica + metal pipeline serve as the second electrode by principle. Direct installation on pure plastic pipe is strictly prohibited. Metal adapter sleeve must be fitted for plastic pipelines, otherwise measurement fails.

🧪 Operating Principle

Two-electrode conductivity method: The metal tip of the sensor acts as electrode 1. The sensor housing and metal pipeline together form electrode 2. Voltage is applied between electrodes, and medium current is measured to calculate conductivity.

Característica: No fixed cell constant. Readings are affected by pipe inner diameter. CGA calibration gain must be configured after installation. CGA values vary with pipe size (1.5″ ≈96% / 2″≈97% / 3″≈100%).

🎯 Typical Application Scenarios

1. CIP cleaning in food, indústrias de bebidas e farmacêutica: distinguish clean water, alkaline and acid liquid, identify phase transition and automatically determine cleaning endpoint
2. Hygienic pipeline phase separation and tank media switch detection
3. Monitoring of high-electrolyte media (Not suitable for low-conductivity ultra-pure water. Lower limit 100 µS/cm. Use LDL101 for ultra-pure water)

⚠️ Principais limitações & Model Selection Comparison

1. Lower limit 100 µS/cm, cannot measure low-conductivity purified water; select LDL101 for purified / ultra-pure water
2. Metal pipeline or metal liner required; plastic pipe not recommended
3. Measurement is pipe-diameter dependent; on-site CGA calibration is mandatory
4. LDL100: two-electrode hygienic type, G1/2, 100~15000 µS/cm; LDL2xx: inductive type (non-contact, anti-incrustante)

📌 Accessories

Weld bosses, Varivent hygienic adapters E43306 / E43307 / E43310

Metal adapter E43313 (for plastic pipeline retrofit)

🧯 Troubleshooting

1. Drifting / inaccurate readings: Verify metal pipeline; confirm CGA parameter matches pipe diameter; check electrode fouling after CIP
2. Sem sinal: Check M12 pin assignment, DC18~30V supply and polarity; verify IO-Link master version
3. Abnormal temperature: Temperature probe damage or medium temperature exceeding 150 ℃ upper limit

IFM LDL100 Field Application Cases

Posicionamento central: Hygienic two-electrode sensor, mainly for phase interface detection (not for ultra-pure water purity measurement). Range 100~15000 µS/cm, metal pipe installation. Link IO + 4~20mA dual output, built-in temperature measurement, IP69K withstands high-temperature CIP flushing.

Caso 1: Complete CIP System for Food Industry (Official IFM Reference Case)

Indústria: Dairy / beverage system integrator

Processo: In-place pipeline CIP cleaning (Product → Water pre-rinse → Alkaline cleaning → Rinse → Acid cleaning → Final clean water)

Propósito: Phase transition detection, replacing fixed timer control

LDL100 detects sudden conductivity changes in real time: milk (high conductivity) → clean water (baixa condutividade) → alkaline solution (very high conductivity) to automatically determine phase switching points.

Benefícios: Replace fixed timing; move to next phase only when conductivity meets rinse criteria. Reduces water, chemical and heat consumption, shortens CIP cycle, prevents residual chemical contamination of finished products. IO-Link uploads real-time conductivity and temperature for HMI monitoring and diagnostic.

Key point: Install on stainless steel hygienic pipeline, configure CGA diameter calibration factor during commissioning.

Caso 2: Phase Separation & Product Recovery in Juice / Beverage Lines

Indústria: Fruit juice, concentrated beverage, plant-based drink

Processo: Batch pipeline switching, separating product and rinse water

Propósito: Detect interface between product and water to reduce product loss

Significant conductivity difference between different media. LDL100 captures phase interface signal to trigger valve switching, fully divert product stream to storage tank and avoid discharging large amount of product to waste water; also verify rinse completeness.

Vantagens: Hygienic Ra≤0.8 μm, withstand short-time CIP temperature up to 150 ℃, no separate transmitter required to save cabinet space.

Limitação: Only for metal pipelines; metal liner required for plastic pipe.

Caso 3: CIP/SIP Endpoint Verification for Pharmaceutical Preparation Lines

Indústria: Biopharma, oral dosage (non ultra-pure water loop)

Processo: CIP cleaning for preparation pipelines, rinse validation for acid/alkaline detergent

Propósito: Confirm complete removal of cleaning chemicals for GMP cleaning validation

LDL100 monitors rinse water conductivity. When conductivity drops below threshold, cleaning is deemed qualified. Conductivity and temperature history can be logged for GMP audit trail.

Observação: Not for purified / ultra-pure water loop (<100 µS/cm), use LDL101 instead.

Caso 4: Salinity & Ion Monitoring for Cooling / Process Circulating Water in Food Plants

Indústria: Food plant utility system

Processo: Stainless steel cooling water circulation system

Propósito: Monitor ion / salt concentration of circulating water and provide early warning for scaling and corrosion risk

Rising ion concentration of circulating water increases conductivity. LDL100 outputs signal to trigger blowdown / water makeup, while acquiring medium temperature for compensation.

Suitable for medium-conductivity circulating water; not for ultra-pure water.

Caso 5: Pipeline Media Switching for Sauce & Cheese Production

Indústria: Dairy, sauce (ketchup, salad dressing)

Processo: Batch production, switching among product, rinse water and cleaning liquid inside pipeline

Propósito: Prevent cross-contamination between batches by automatic phase separation

Sauce conductivity is much higher than clean water. The sensor detects the interface and switches flow direction automatically to reduce cross-contamination between different products. It also monitors concentration range of acid/alkaline detergent during CIP.

In cheese factory CIP projects, LDL series verifies complete detergent flushing to guarantee milk product safety.

Caso 6: Industrial Parts Cleaning Line (Hygienic Metal Cleaning Loop)

Indústria: Precision food machinery / pharmaceutical equipment parts cleaning

Processo: Metal workpiece spray cleaning, alkaline wash → rinse

Propósito: Monitor outlet pipeline of cleaning tank to verify full alkaline rinse-out

High conductivity of waste cleaning liquid; conductivity drops after rinsing with clean water. LDL100 judges rinse endpoint. IO-Link supports remote parameter reading and fouling diagnosis.

❌ Cenários inadequados (Armadilhas na seleção de modelos)

1. Ultra-pure water / purified water (conductivity ＜100 µS/cm, below measuring range; select LDL101)
2. All-plastic pipeline (no metal as second electrode, measurement impossible; metal sleeve required)
3. Heavy fouling / abrasive media (fouling changes electrode cell constant; LDL2xx inductive non-contact type recommended)

✅ General Commissioning Notes for All Cases

1. Instalação: Prefer rising pipe to maintain full pipe without air bubbles; mount at 45° for horizontal pipe
2. CGA gain calibration must be performed and matched with pipe inner diameter
3. Temperature compensation parameter T.cmp set according to ion characteristics of medium
4. IO-Link accesses conductivity, medium temperature and sensor diagnostic data simultaneously

IFM LDL100 CIP PLC Control Logic with Phase Switch Threshold Examples

Aplicativo: CIP for dairy / beverage hygienic pipeline. LDL100 sensor, saída: 4~20mA or IO-Link reading of conductivity (µS/cm) + temperatura média. PLC switches CIP sequence automatically based on conductivity threshold instead of fixed timer.

Condição prévia: LDL100 CGA diameter calibration completed, pipeline full of liquid without air bubbles.

1. Reference Thresholds (Field fine-tuning required based on actual medium)

Observações:

Thresholds are for engineering reference only. Values vary with medium, concentration and temperature, must be calibrated on site.

Add delay filtering (5~10s stable judgement) to avoid false valve switching caused by instantaneous conductivity spikes from air bubbles.

2. PLC Logic Framework (Ladder Diagram Concept)
3. Signal Acquisition

IO-Link readout: LDL100 → Conductivity value (µS/cm), temperatura média, sensor status bit (falta / ok)

4~20mA mode: AI module sampling, convert to conductivity; read temperature channel separately

2. Fault Interlock

Sensor fault bit =1: suspend automatic CIP sequence, trigger HMI alarm, disable automatic phase transition

Medium temperature＞150℃: alarme de sobretemperatura (LDL100 upper limit 150℃)

3. Process State Machine

State machine mode with sequential forward transition only, no skip allowed.

Transition condition for each stage: Conductivity threshold met + stable delay + sensor healthy

4. HMI Functions

Real-time trend: Condutividade & temperature history curve for GMP audit trail

Parameter screen: Adjustable conductivity thresholds and delay time for each stage

Alarms: Conductivity out of range, ruptura do fio do sensor, temperatura excessiva, CIP timeout

5. Safety Backup

Max timer for each stage. Por exemplo, max alkaline cleaning duration 30 min. Force alarm and safety drain upon timeout regardless of conductivity value, preventing process lockup.

3. Typical Interlock Logic Example (Stage Transition)

Exemplo: Pre-rinse → Alkaline cleaning

SE (Conductivity ≤1500 µS/cm) AND (Sensor_OK) AND (Stable for 10s) THEN

Close pre-rinse inlet valve

Open alkaline supply valve

Set CIP state to 【Alkaline Cleaning Stage】

END_IF

4. LDL100-Specific Commissioning Notes
5. Re-run CGA gain calibration every time pipe inner diameter changes, otherwise reading deviation causes wrong phase switch
6. Air bubbles cause violent conductivity fluctuation. Install sensor at full-pipe location, avoid high points with air pockets
7. Keep temperature compensation enabled for high-temperature CIP/SIP; LDL100 performs internal conductivity compensation
8. Electrode fouling leads to reading drift. Program can add periodic maintenance reminder (triggered by accumulated CIP cycles)
9. Optional Extended Logic

Log peak / minimum conductivity, duration of each stage into audit trail database (GMP pharmaceutical projects)

Automatic maintenance alert: Trigger probe cleaning prompt when baseline conductivity drifts beyond set percentage under identical medium