DQYYFP4/6 Core 0.2 mm² Shielded Liquid Level Sensor Cable with PTFE Vent Tube – Corrosion Resistant Submersible Wire for Wastewater & Chemical Tanks

The Headache of Inaccurate Readings and Rotted Cables

You run a facility that depends on precise liquid level measurements. Maybe it is a wastewater treatment plant. Maybe it is a chemical storage tank. Or maybe it is an oil reservoir. You know the problem very well. You install a sensor cable, and for a few months, everything works fine. Then, the readings start to drift. The numbers do not make sense. You check the sensor, and it looks fine. But the cable is the silent killer.Why does this happen? Two big reasons. First, moisture and chemicals eat through the jacket. This is “creep corrosion.” It starts small, but soon the shield fails. Second, pressure changes mess up your data. If the cable cannot “breathe,” the pressure on the sensor diaphragm is wrong. You get false highs or false lows. This causes process errors, spills, or shutdowns. You lose money every time you have to pull a tank apart to fix a rotted cable. You need a cable that fights back. You need a cable that vents pressure but keeps liquids out.

A Cable That Breathes: The Vent Tube Solution

This is not just a standard shielded wire. This is a specialized tool for your submersible transmitters. The secret is inside the core. We build a dedicated vent tube right into the cable structure. This tube runs the full length of the cable. It connects the air inside the sensor to the atmosphere above the liquid.Here is how it helps you. When the liquid level rises, the air pressure pushes down. Without a vent, this pressure crushes the sensor or gives a wrong reading. With our vent tube, the air escapes or enters freely. The sensor only measures the liquid’s weight, not the air pressure. This gives you true, gauge-referenced data. It is critical for deep wells and tanks where barometric pressure changes daily.But we do not stop there. We use expanded PTFE (ePTFE) membranes for the venting. Why PTFE? Because it is a magic material for harsh environments. It is hydrophobic. This means water and sludge cannot get in. But air and gas can pass through easily. It acts like a one-way valve for air. It stops the “permeation” issue you see in cheap plastic cables. In chemical plants handling Hydrochloric Acid or strong solvents, standard PVC jackets fail. They let gases through, which corrode the steel pipe or the sensor housing. Our PTFE lining stops this completely.

Built Like a Tank: Construction and Materials

Let us look under the hood. We do not cut corners on materials. We know you need reliability for 5 to 10 years.

The Conductor Core

We use high-purity stranded copper. Not just any copper, but tinned or silver-plated copper strands. Why? Because flexibility matters. You pull this cable down a narrow well casing. If it is stiff solid core, it might snap or kink. Our 0.2 square mm cores are fine enough to be flexible but thick enough to carry the 4-20mA signal without voltage drop over long distances. We offer 4-core and 6-core options. The extra cores are for power, ground, or a second sensor signal.

The Insulation and Shielding

Each tiny copper wire is wrapped in insulation. We use Foamed Polyethylene (PE) or PTFE for this. Foamed PE is great because it lowers the capacitance. This keeps the signal clean and fast. Over that, we wrap a shield. Usually, this is a copper braid plus an aluminum foil layer. This double shield stops Electromagnetic Interference (EMI). If you have big pumps or VFDs (Variable Frequency Drives) nearby, they create noise. Our shield stops that noise from messing up your delicate sensor signal.

The Armor and Jacket

This is the muscle. For submersible applications, we add armor. It might be stainless steel wire armor (SWA) or steel tape armor (STA). This protects the cable if it gets snagged on a rock or chewed by a rodent. But the real star is the outer sheath. We use FEP (Fluorinated Ethylene Propylene) or a special PUR/TPU blend. These materials resist oil, abrasion, and UV light. If you are in a cold climate, we use a low-temperature PVC that stays flexible down to -40°C. It will not crack when you pull it in winter.

Technical Specifications Table

Here is the hard data you need for your engineering team. We can customize these, but this is our standard high-performance spec for the DQYYFP series:

Where This Cable Shines: Real World Use Cases

You might ask, “Do I really need this specific cable?” If you are in one of these spots, the answer is YES.

Wastewater and Sewage Treatment

This is the toughest environment. You have hydrogen sulfide gas, acidic sludge, and constant moisture. Standard PVC cables get “soggy.” The water soaks into the insulation over time. Our PTFE-vented cable stops the gas permeation. The vent tube keeps the pressure equalized as the water level changes in the wet well. You get accurate pump control without corrosion failures.

Chemical Processing and Acid Tanks

Are you measuring levels in a Hydrochloric Acid or Caustic Soda tank? If the cable jacket is not PTFE or FEP, the acid will eat it. Even worse, if the cable is not vented, the chemical fumes can permeate the jacket and corrode the sensor from the inside out. We use a UHP (Ultra High Performance) venting system. It mimics the old ICI EDS.PIP.53.01 spec. It vents the gas safely but keeps the liquid acid out.

Oil and Gas / Fuel Storage

In fuel tanks, you have volatile organic compounds (VOCs). These gases can build up pressure. If your sensor cable blocks the pressure, the reading is wrong. Also, fuel can degrade cheap rubber jackets. Our FEP outer sheath is impervious to diesel and gasoline. The stainless steel armor prevents damage during tank cleaning operations.

Food and Pharma (CIP/SIP)

If you use Clean-In-Place (CIP) systems, you blast the tank with hot steam and caustic cleaners. A normal cable melts or cracks. Our high-temp silicone or PTFE jackets survive the steam. The smooth sheath prevents bacteria from growing in cracks, meeting strict hygiene standards.

Why Our Venting System is Better

You will see cheap “vented cables” from other traders. They just poke a hole in the jacket and cover it with tape. That is a disaster waiting to happen. Liquid will seep in through the hole eventually.Our system is engineered. We use a hydrophobic PTFE membrane at the vent opening.

1. Liquid Block: Surface tension stops water and oil from entering.
2. Gas Flow: Air and vapor pass through the microscopic pores freely.
3. Self-Cleaning: The membrane structure resists clogging from dust or sludge.

We also use a “fibonacci” or bundled laying-up for the internal cores. This keeps the vent tube open and separate from the signal wires. It never gets pinched or crushed during installation.

Installation Tips for Longevity

To get the 10-year life out of this cable, follow these simple rules during install:

1. Seal the End: When you cut the cable to length, you must seal the end of the vent tube immediately. Use a specialized heat-shrink cap or silicone sealant. Do not let concrete or grout fall into the vent tube.
2. Avoid Kinks: Do not bend the cable tighter than 8 times its diameter. Kinking collapses the vent tube and breaks the shield.
3. Strain Relief: Use a cable gland with a strain relief boot at the junction box. The weight of the cable in a deep well is heavy. Do not let the electronics take the weight.
4. Check the Plug: If you are using a submersible probe with a vent plug (like a Gore-Tex plug), ensure it is facing down or sideways, not pointing up at the tank roof where drips can hit it.

Compliance and Quality Control

We do not guess on quality. Every batch of DQYYFP cable is tested.

• Spark Test: We check the insulation for pinholes at high voltage.
• Shield Continuity: We verify the braid is connected properly.
• Vent Flow Test: We blow air through the vent tube to ensure it is not blocked.
• Aging Test: We bake samples in an oven to simulate 10 years of use.

Our cables meet international standards. We can provide certificates for ISO 9001, CE, RoHS, and REACH. If you need UL or CSA for North America, we can arrange that testing. We use raw materials from trusted suppliers (like Polycab or Lapp standards) to ensure consistency.

The Bottom Line: Save Money on Maintenance

Yes, this cable costs more than a standard RVVP shielded wire. But think about the total cost. A cheap cable fails in 6 months. You pay for the part, the labor to pull it, and the downtime of your tank. That happens two or three times, and you have paid for our premium cable.Our DQYYFP4/6 cable lasts 5 to 10 years. It keeps your sensors accurate. It stops corrosion before it starts. It is a “fit and forget” solution.

Ready to Solve Your Cable Problems?

Do not let corrosion or bad data slow you down. We have this cable in stock in 100-meter coils, or we can make custom lengths with specific connectors (like M12, M16, or Deutsch connectors) molded on.Tell us your specific needs:

• What liquid are you measuring?
• What is the maximum temperature?
• How deep is the tank?
• Do you need armor?

Send us an inquiry today. We will send you a detailed quotation and a free sample of the cable cross-section so you can see the vent tube quality for yourself. Let us build the last liquid level cable you will ever need to buy.Get a Quote Now: [Your Email Here]