F-235 Sterilizable pH Electrode

Name: F-235 Sterilizable pH Sensor
SKU: F-235
Availability: InStock

F-235 Sterilizable pH Sensor

The Model F-235 FermProbe® pH sensor is steam sterilizable and autoclavable for use in bioprocess applications. The F-235 style may be used in either benchtop or production vessels.

Available with Integral RTD, either Pt-100 or Pt-1000

Low impedance HT3 glass bulb with low sodium ion error

USP grade cellulosic thickener used for reference gel.

The F-235 Sterilizable pH Sensor is a sealed, gel-filled, sterilizable, autoclavable design with built-in temperature element. This allows for the automatic compensation of Nernstian temperature effects in processes with wide pH ranges and significant temperature shifts.

The VarioPin connector allows for a multiple connection; both pH signal and temperature signal in the same wiring harness. The temperature element is either a PT100 or PT1000 Platinum Resistance Device, which are compatible with the majority of commercially available instruments. The unique construction methods used by Broadley-James allows this sterilizable pH sensor to operate at pressures of up to 10bar (150psig) and temperatures up to 135°C.

Features of the F-235

Integrated Temperature element for Nernstian temperature compensation.
Double-Junction Silver/Silver Chloride reference element for the ultimate in stability and resistance to contamination.
Specifically designed for multiple SIP, CIP, or Autoclave cycles. Withstands exposure to harsh CIP solutions.
Metric threaded cap is compatible with a wide range of bioprocess sensor housings.
Rugged, low-impedance pH bulb provides fast and precise pH measurements even after prolonged steam exposure.

F-235 Sterilizable pH Sensor Specifications

Measurement Range	0–14 pH
Operational Temp. Range	-5°–135° C [23°–275° F]
Operational Pressure Range	0-7750 mmHg [0-150 psig]
Storage Temperature	5°–50° C [41°–122° F]
Shelf Life	12 months
Sensor Connectors	V6 Variopin, Coaxially Shielded
Sensor Connector Cable	AX-2000-VP-XXXX series

Wetted Materials

O-ring	FDA Compliant Silicone
pH Glass Sensor	Lead-free Glass
Ceramic Junction	Alumina Silicate

Sensor Housings

We would recommend the following Broadley-James sensor housings for use with the F-235 FermProbe^{^{^®}} sterilizable pH probe:

Model 335 Sensor Unguarded Housing – Standard 25mm (Pg 13.5), typical vessel insertion lengths 52mm & 128mm
Model 325 Sensor Guarded Housing – Standard 25mm (Pg 13.5), typical vessel insertion lengths 37mm & 113mm
Model 346 Sensor Unguarded Housing – Sartorius Safety Port 25 mm (Pg13.5), typical vessel insertion length 25mm
Model 356 Sensor Guarded Housing – Sartorius Safety Port 25 mm (Pg13.5), typical vessel insertion length 40mm

Compatible Cables

This multifunctional sensor is capable of both receiving and processing a number of signals at the same time. The Variopin (VP) connector allows simultaneous pH and temperature readings. We recommend the following cables for use with the F-235 FermProbe^{^{^®}} sterilizable pH probe:

Cable Type	Sensor Connector & Device Connector	Device Terminal
VP plug to Ferrules

Choose Sensor Model

If the sensor needs to fit an existing cable, check cable connector. If it has a multipin connector, an F-235 or F-285 FermProbe is required. Another guideline is to note the connector’s color. If the cable connector is all stainless steel, use the F-235 or F-285 FermProbe. The F-235 and F-285 sensors also have an integrated temperature sensor that can be used for automatic temperature compensation.

Choose Sensor Length

Benchtop Applications

The sensor length is from the base of the cap to the tip of the sensor (the glass part of the sensor).

SIP Tank Applications

If you have already chosen a sensor housing, select an sensor length with the same Class designation as the housing. The housing ordering information box also lists the correct sensor length to order. If you have not already chosen the housing, please review the recommendations next to each sensor model below.

Confirm Cable Length and Connector

Model F-235 pH sensors require disconnect cable and connector assemblies.

Ordering Information

Model F-235 pH FermProbe with Standard Metric Cap

Sensor Model	Use with these housing models or benchtop vessel sizes	Temperature sensor type	Sensor Length	Cable Length	Connector Type VP	Sensor Part Number
F-235	325, 335 Class D<1L Vessel	Pt 100	120mm	Order Separately		F-235-D120-VP
		Pt 1000				F-235-H120-VP
F-235	325, 335 Class F1-3L Vessel	Pt 100	200mm			F-235-D200-VP
		Pt 1000				F-235-H200-VP
F-235	3L-5L Vessel	Pt 100	225mm			F-235-D225-VP
		Pt 1000				F-235-H225-VP
F-235	7L-15L Vessel	Pt 100	325mm			F-235-D325-VP
		Pt 1000				F-235-H325-VP

Note: the vessel sizes are for guidance only – check your own vessel dimensions or the length of the sensor you are replacing.

FAQs

How Should FermProbes Be Stored?

Never store a pH sensor dry. The first choice for storing FermProbes is KCl solution. We recommend any concentration between 2.0 M and 3.8 M. Another good choice is buffer solution. A pH 4 buffer solution is best since it will keep longer, but pH 7 is also acceptable. If it is necessary to clean a FermProbe with acid, caustic, solvent or other cleaning solution, it is best to soak the sensor in KCl solution after cleaning and prior to use or calibration. This will re-condition the bulb and reference, extending the sensor life and improving calibration accuracy.

What's inside a FermProbe?

The gel in a FermProbe^® is a non-toxic, USP grade, organic material. Other manufacturers may use different materials such as polyacrylamide. Please call us for more information or an MSDS.

What is a pH Sensors Life Expectancy?

How long should a sensor last in storage?

Fermprobes can be stored for up to one year from date of shipment with no appreciable change in their performance or expected service life. After a year, the sensors are still good but their potential for optimum performance slowly erodes until they finally become totally non-functional. This would usually take many years of storage. Most customers try to rotate stock so sensors are put into service prior to one year from shipment, and this would be our strong recommendation for most customers.

How long should a sensor last in actual service?

Fermprobe pH sensors exhibit a fairly predictable "lifetime vs. temperature" performance ratio. The higher the temperature, the shorter the life; and, the longer the duration of exposure to elevated temperature, the shorter the life. Maximum temperature advisable is 135°C.

For example:

A Fermprobe may last 40 sterilization cycles at 121°C for 30minutes. (20 hours at 121°C)
A Fermprobe may last 20 sterilization cycles at 121°C for 60minutes. (20 hours at 121°C)
A Fermprobe may last 20 sterilization cycles at 135°C for 30minutes. (10 hours at 135°C)
A Fermprobe may last 10 sterilization cycles at 135°C for 60minutes. (10 hours at 135°C)

The actual service life attained will depend upon all other considerations, such as whether or not there is a CIP cycle (strong, hot caustics can dissolve the glass and the ceramic), whether or not the sensor is exposed to high pressure or fast flow rates, whether or not there are abrasives in the sample, etc.. Since there are so many variables and factors involved in determining sensor life, an operator can best determine the life for his particular vessel and set of conditions experimentally. By careful recording of when the sensors are installed and a statistical analysis of typical life, one can determine the optimum number of cycles.

There is a normal variance in sensor life and most operators of production vessels will search out a number, perhaps 10 cycles, that gives them a maximum confidence in the ability to run a cycle without failure. It is a helpful exercise to take the cost of the sensor and divide it by the number of cycles, then look at this "cost per cycle" to see if it is justifiable for a particular product.