Rapidox 6100 C4-FN & C5-FK Multi-Gas Pumpback — Analyser for SF6-Alternative Gas Mixtures

Fully automatic pump-back analyzer for eco-friendly C4-FN and C5-FK gas mixtures used in next-generation switchgear.

Overview

The Rapidox 6100 C4-FN & C5-FK Multi-Gas Pumpback is a portable analyser from the British company Cambridge Sensotec for SF6-free gas-insulated equipment. It tests mixtures based on C4-FN (g3, Novec 4710) and C5-FK (AirPlus, Novec 5110), which switchgear and circuit breaker manufacturers use to replace SF6.

In one cycle the instrument measures mixture purity, carrier gas content, moisture and CO. After the measurement the sample is returned to the equipment, so no gas is lost or released to atmosphere.

Why C4-FN and C5-FK need to be monitored

Alternative gases are not used pure but in mixtures. C4-FN is usually blended with CO₂ and O₂, C5-FK with CO₂ and air. Insulating performance depends on the exact ratio, so the mixture must be checked after filling, topping up and repair.

What regular analysis gives you:

• Mixture composition. A drop in C4-FN or C5-FK content lowers the dielectric strength of the insulation.
• Moisture. Water in the compartment degrades insulation and speeds up gas decomposition.
• CO. Carbon monoxide is the main decomposition product from arcing and partial discharge. A rise signals a problem inside the apparatus.
• Personnel safety. Decomposition products are toxic, so their level is checked before a compartment is opened.

According to Cambridge Sensotec, these gases have a much lower global warming potential than SF6 but remain harmful to the atmosphere. Their release during testing is therefore controlled as strictly as for SF6.

How a measurement works

1. The operator connects the instrument to the compartment or cylinder through a Rectus-style fitting (DN8 and DN20 adaptors supplied) and selects the mixture type on screen.
2. If the instrument was previously used with another gas, it runs a purge and sends the remainder to an external recovery bag.
3. The Rapidox draws a small amount of pressurised gas. A vacuum purge and internal storage keep air out of the sample.
4. All gases are measured simultaneously; a stable reading takes a few minutes.
5. The compressor returns the gas to the equipment at up to 10 bar. Results are shown on screen, logged and printed if required.

Built-in safety features make sure the cycle completes without gas loss or cross-contamination.

Sensors and ranges

Parameter	Range	Accuracy	Sensor type	Calibration	Life span
C4-FN / C5-FK	0–20 %	±0.5 %	IR	12–24 months	over 5 years
CO₂	0–100 %	±0.5 %	IR	12–24 months	over 5 years
Air / O₂ / N₂	0–100 % air, 0–30 % O₂	±1 % FS	electrochemical	12–24 months	up to 5 years
H₂O (dew point)	-60 to +20 °Cdp (10–24,000 ppmV)	±2 °Cdp	polymer	12 months (sensor exchange)	2–3 years
CO	0–500, 0–1,000, 0–2,000, 0–5,000 ppm	±2 % FS	electrochemical	12–24 months	up to 5 years

Moisture is shown as dew point or ppmV, corrected to the actual temperature or to 20 °C. One configuration can analyse up to six gases per mixture type. The sensor set is chosen at ordering and can be extended later.

Technical specifications

Parameter	Value
Measurement time	2–8 min (min. 6 min for H₂O)
Warm-up	3–4 min at 20 °C, 15 min for full accuracy
Inlet pressure	0.5–35 bar (up to 10 bar in pump-back mode)
Sample flow	0.5 L/min
Pump-back compressor	up to 10 bar, up to 25 cycles per charge at 20 °C
Display	7" (178 mm) colour LCD touch screen
Printer	built-in thermal printer
Memory	4 GB, about one year of continuous logging
Data export	Excel-compatible files to a USB stick
Sample connection	Rectus-style fitting, DN8 and DN20 adaptors
Power	lithium battery up to 8 h, 4–6 h charge, mains 90–260 V
Operating conditions	-10 to +40 °C, 10–90 % RH, 600–1100 mbar
Housing	IP66 Peli case with trolley and handles
Dimensions	270 × 560 × 450 mm (H × W × D)
Weight	21 kg with case

Rapidox 6100 models compared

Model	Gases	Best for
Rapidox SF6 6100 Pump Back	SF6	SF6-only fleets
Rapidox 6100 Clean Air	technical air (N₂/O₂)	Clean Air insulated equipment
Rapidox 6100 C4-FN & C5-FK	C4-FN and C5-FK mixtures	g3 and AirPlus equipment
Rapidox 6100 QU4D	SF6, C4-FN, C5-FK, Clean Air	Mixed fleets, one instrument for all gases

What is included

• Rapidox 6100 C4-FN & C5-FK analyser in a Peli case with trolley;
• sample hoses;
• DN8 and DN20 adaptors;
• charger;
• user manual.

Optional: gas recovery bag, hose and adaptor kit, calibration gas mixtures.

Supply in Kazakhstan

KEG TRK supplies Cambridge Sensotec analysers to power utilities and contractors who service gas-insulated switchgear. We help choose the sensor configuration for your equipment fleet and select adaptors for your apparatus. Price on request.