15 mm RCE Corrosion Cell Selection Guide

Last Updated: 9/8/20 by Neil Spinner

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1Abstract

This application note discusses the selection of components useful to evaluate mass transport limited corrosion under flow conditions. The RCE system components described here align with recommendations by the ASTM G5 Standard. Users should refer to Pine Research application note DRA10011, titled "Study of Mass Transport Limited Corrosion with Rotating Cylinder Electrodes" for a more in-depth discussion of the theory and governing equations.

2Introduction

A convenient instrument for rapidly moving a metal sample with respect to a fluid is the Rotating Cylinder Electrode (RCE). This apparatus includes an electrode rotator, RCE electrode shaft, and accessories (see Figure 1) capable of precisely adjusting the rotation rate of a vertically-oriented shaft. A special tip capable of holding a cylindrical-shaped metal sample is mounted at the lower end of the shaft. The tip is fashioned primarily from chemically-inert and electrically-insulating materials (including polyether ether ketone, PEEK), but buried within the tip is a metal shank that provides mechanical stability and also electrical contact with the metal cylinder sample, which is also called a metal coupon.

Figure 1. Typical Rotating Cylinder Setup for Corrosion Analysis

As shown in Figure 1, the primary components of a typical RCE system include the following items:

An analytical electrode rotator (Pine Research MSR Electrode Rotator, Modulated Speed Rotator (MSR) part number AFMSRCE). The rotator sets the rotation rate of the RCE cylinder (coupon).
A shaft to hold the RCE cylinder (part number AFE9MBA) Precision 15 mm Single RCE Shaft and connect electrically through the rotator to the potentiostat where corrosion rate can be measured.
RCE cylinder inserts (coupon) 15 mm OD Cylinder Inserts that have a 3 cm² exposed area and are made from the specific metal of interest.
An OpenTop glass cell OpenTop Cell with Water Jacket that integrates easy access for purge gas control, as well as insertion and positioning of other electrodes (counter and reference) and accessories.
A manner by which to control temperature, commonly a water jacket around the glass electrochemical cell or directly by means of a hotplate beneath the glass cell.
A potentiostat to measure and record corrosion current. WaveDriver 100 EIS Potentiostat/Galvanostat

There are many items required for a complete 15 mm RCE setup. It can be challenging to know which parts should be ordered when a new setup is desired. Pine Research has tried to streamline the process with product bundles, which are groups of pre-selected items to fulfill the needs of most RCE corrosion scientists with a single part number. This guide mirrors the website and product selection is detailed in the flow chart provided (see Figure 2).

Figure 2. Flow of Products for a Complete 15 mm RCE Setup. User Input Required at Shaded Boxes

315 mm RCE System Bundles

To ease the complication of piecing items together to build a complete RCE system, Pine Research has created bundles. A bundle is a grouping of items that have been pre-selected to make a complete RCE setup, under a single part number. Each RCE bundle includes the basic accessories needed to perform flow based corrosion measurements at a rotating cylinder electrode. The 15 mm RCE product bundles are provided on our website under the "Corrosion Products" category. They are also provided below in Table 1 for reference. Product bundles offer an additional discount beyond ordering the components in a piece-wise fashion. As described in Table 1, there are eight 15 mm RCE bundles. Each bundle includes the following items:

Cell kit, which contains the OpenTop cell and components (OpenTop cell lid, adapters, ribbon clamp, cell clamps, and PTFE stoppers). There are four different cell kits available (all cells are 1 L volume and compatible with the 15 mm RCE accessories):
- Jacketed cell with drain valve (part number AFCELL8) OpenTop Cell with Water Jacket and Drain Valve
- Jacketed cell without drain valve (part number AFCELL8U3) OpenTop Cell with Water Jacket
- Basic (unjacketed) cell with drain valve (part number AFCELL8U) OpenTop Cell with Drain Valve
- Basic (unjacketed) cell without drain valve (part number AFCELL8U2) OpenTop Cell
Hose barb/drain valve accessories are included as appropriate for the chosen cell
15 mm single cylinder RCE shaft (part number AFE9MBA) Precision 15 mm Single RCE Shaft with gas-purged taper plug assembly (part number AC01TPA6M) Gas-Purged Bearing Assembly
Graphite counter electrode (part number AFCTR3) Large Graphite Counter Electrode Assembly
Luggin capillary (part number RRPG031) Luggin Tube for reference electrode (reference electrode not included) Standard Size Reference Electrodes
Dual port gas purge/sparge accessory (part number RRPG034) Dual Port Gas Inlet, 24/25

Bundle Code/ Part Number	Description
[RCE15-JV] RCE Bundle with Jacketed Cell with Drain Valve	15 mm RCE Bundle - jacketed cell with drain valve Includes cell kit: AFCELL8 OpenTop Cell with Water Jacket and Drain Valve
[RCE15-RJV] Complete RCE Bundle with Rotator and Jacketed Cell with Drain Valve	15 mm RCE Bundle - jacketed cell with drain valve, includes rotator Modulated Speed Rotator (MSR) Includes cell kit: AFCELL8 OpenTop Cell with Water Jacket and Drain Valve
[RCE15-J] RCE Bundle with Jacketed Cell	15 mm RCE Bundle - jacketed cell without drain valve Includes cell kit: AFCELL8U3 OpenTop Cell with Water Jacket
[RCE15-RJ] Complete RCE Bundle with Rotator and Jacketed Cell	15 mm RCE Bundle - jacketed cell without drain valve, includes rotator Modulated Speed Rotator (MSR) Includes cell kit: AFCELL8U3 OpenTop Cell with Water Jacket
[RCE15-V] RCE Bundle with Cell with Drain Valve	15 mm RCE Bundle - basic (unjacketed) cell with drain valve Includes cell kit: AFCELL8U OpenTop Cell with Drain Valve
[RCE15-RV] Complete RCE Bundle with Rotator and Cell with Drain Valve	15 mm RCE Bundle - basic (unjacketed) cell with drain valve, includes rotator Modulated Speed Rotator (MSR) Includes cell kit: AFCELL8U OpenTop Cell with Drain Valve
[RCE15-X] RCE Bundle with Basic Cell	15 mm RCE Bundle - basic (unjacketed) cell without drain valve Includes cell kit: AFCELL8U2 OpenTop Cell
[RCE15-R] Complete RCE Bundle with Rotator and Basic Cell	15 mm RCE Bundle - basic (unjacketed) cell without drain valve, includes rotator Modulated Speed Rotator (MSR) Includes cell kit: AFCELL8U2 OpenTop Cell

Table 1. 15 mm Rotating Cylinder Electrode Product Bundles

For illustration, a photo of all items included in the [RCE15-J] product bundle is shown below (see Figure 3). The bundles are designed for the general case of most RCE users. Each individual component of a complete 15 mm RCE Corrosion System can be replaced and ordered individually.

Should you have a specific request and do not see what you need in a bundle, please contact us. We are happy to provide custom products for your corrosion research needs. If possible, it is best to modify an existing product bundle than to create one from scratch. Our sales team is eager to learn about your research – so give us a call to customize your 15 mm RCE product bundle.


Code	Description
A	PTFE OpenTop Lid
B	Hoobler-Sagi Lid Clamp (set of 3)
C	OpenTop Cell (user chooses configuration)
D	Ribbon Clamp and Cross Clamp
E	Graphite Counter Electrode (part number AFCTR3) Large Graphite Counter Electrode Assembly
F	15 mm Single Cylinder RCE Shaft (part number AFE9MBA) Precision 15 mm Single RCE Shaft
G	Gas-Purged Bearing Assembly (part number AC01TPA6M) Gas-Purged Bearing Assembly
H	MutaPort Adapters for OpenTop Lid (1x cap, 1x 14/20, 6x 24/25)
I	PTFE Stoppers (set of 7)
J	Luggin Capillary Tube for Reference Electrode (part number RRPG031) Luggin Tube
K	Dual Port Gas Purge/Sparge Tube (part number RRPG034) Dual Port Gas Inlet, 24/25

Figure 3. Components of the 15 mm RCE Corrosion Cell

4Major RCE System Components

4.1Electrode Rotator

The industry standard for electrode rotation is the Pine Research MSR Rotator (part number AFMSRCE) (see Figure 4). The MSR Rotator is a major component of an RCE system. Briefly, the MSR Rotator consists of the following primary components:

A motor head, into which the 15 mm RCE shaft is installed
A control box that connects to the motor head, with which rotation rate of the shaft/cylinder is controlled
A cable to connect control box to motor head
An AC power cable that connects to the control box
Polymer base and enclosure, into which the motor and cell are installed on stainless steel support rods. The enclosure is secured by four metal posts on the walls


Code	Description
A	MSR Motor
B	MSR Control Box
C	MSR Control Cable (HD15)
D	Polymer Base and Enclosure

Figure 4. MSR Electrode Rotator

The MSR is compatible with most international power standards (100 to 240 VAC, +/-10%, 50 or 60 Hz, 2 Amps); therefore, users must select the appropriate AC power cord to fit the outlets in the country of use. Pine Research offers US and most international AC power cords. Consult the website for a full list of power cords. You will specify the power cord needed by its part number at the time of order (please contact us with any special cord needs if you do not find the appropriate cord for your country).

4.2Rotating Electrode Shaft for Cylinders and Bearing Assembly

The single cylinder RCE shaft (part number AFE9MBA) (see Figure 5) connects to the motor head on the ¼” stainless steel end. A metal cylinder insert (coupon) installs on the opposite end, and is electrically coupled to the shaft and then to the rotator brushes. The potentiostat working electrode cell cable connects to the top brush contact(s) on the MSR motor. This arrangement offers flexibility in RCE cylinder configuration. The RCE shaft body is made of polyether ether ketone (PEEK). PEEK is chemically compatible in a wide variety of solvent systems and can be used safely up to 80°C.

Figure 5. Single 15 mm Cylinder RCE Shaft (pictured with installed metal cylinder)

Due to the nature of the corrosive environment in which RCE system components are exposed, a corrosion-resistant gas-purged bearing assembly (part number AC01TPA6M) (see Figure 6) interfaces the shaft to the electrochemical cell and lid. It is precision-machined to fit the 15 mm RCE shaft body. It is made of PEEK and its bearings are ceramic to avoid corrosion. The bearing assembly has an inset fluoroelastomer rubber O-ring to create a seal and a gas purge barb at the junction of the assembly. The tapered assembly fits standard 24/25 or 24/40 tapered joints. The central hole in the corrosion cell OpenTop (see Figure 3) lid is a 24 mm opening, designed to accommodate the bearing assembly and RCE shaft. When all other ports of the cell are closed, a slight positive pressure can be maintained in the cell when the gas-purged bearing assembly is used.

Gas-Purged Bearing Assembly for Rotating Disk Electrode Shaft

Figure 6. Gas-Purged Bearing Assembly for 15 mm RCE Setup

The bearing assembly should be installed onto the shaft before the shaft is installed into the MSR rotator (see Figure 7). Slide the tapered end over the ¼” stainless steel 15 mm RCE shaft and slide down onto the PEEK shroud of the shaft. A retaining ring on the shaft will keep the bearing assembly in place during its installation into the MSR Rotator.

Figure 7. Installation of Gas-Purged Bearing Assembly onto Single Cylinder RCE Shaft

Some users have requested a shaft where two cylinders are installed, such that one cylinder is used to monitor electrochemical corrosion rate (by connection to the potentiostat) and the other is strictly in place for use in weight loss experiments. Pine Research offers a Double Cylinder 15 mm RCE shaft to suit the needs of these researchers (part number AFE9MBDA) (see Figure 8). The 15 mm RCE product bundles are sold with a single cylinder shaft by default. Please inform sales at the time of inquiry if you would instead like the double cylinder shaft or want to add it to your existing product bundle.

Double 15 mm Cylinder RCE Shaft (pictured with two installed metal cylinders)

Figure 8. Double 15 mm Cylinder RCE Shaft (pictured with two installed cylinders)

Cylinder inserts (sold separately) are precision metal samples that fit the 15 mm single and double cylinder RCE shafts. To seal around a cylinder insert installed on the RCE shaft, flat fluoroelastomer washers are used in conjunction with a threaded PEEK nut on the shaft end (see Figure 9). A package of ten fluoroelastomer washers is included with each shaft. Additional washers are available (part number AKE9VWASHER). Washers should be replaced regularly with every other cylinder change to minimize solution leakage and edge corrosion around the cylinders.


Code	Description
A	15 mm Single Cylinder RCE Shaft Precision 15 mm Single RCE Shaft
B	Fluoroelastomer Washer Fluoroelastomer Seal Washers
C	15 mm OD Metal Cylinder Insert (Coupon) 15 mm OD Cylinder Inserts
D	15 mm RCE PEEK Nut

Figure 9. Disassembled Single 15 mm Cylinder RCE Shaft

4.315 mm RCE Cylinder Inserts (Coupons)

Cylinder inserts, also called coupons, install onto both the single and double 15 mm RCE shafts. Generally, the material from which the cylinder is made represents the same material whose field corrosion is the subject of RCE research. It is critical that cylinders be of exact dimensions. When installed onto the RCE shaft, there will be 3 cm² of metal surface exposed to solution.

Pine Research provides a mechanical drawing for 15 mm RCE cylinder inserts (download from our website, also shown below in inches, see Figure 10) for users who choose to machine their own cylinder inserts. Pine Research can custom-fabricate cylinder inserts from almost any non-toxic material, including starting material sent by the customer. Inquire with sales to initiate custom cylinder inserts.

Figure 10. (A) Mechanical Drawing of 15 mm OD Cylinder Inserts; (B) Photo of 15 mm OD Cylinder Inserts

Cylinder inserts are sold in packages of ten (10). Each package includes a certification sheet for the material used to manufacture the cylinder inserts. The cylinder inserts made by Pine Research (see Figure 10) are fabricated from a variety of popular steel alloys (see Table 3 for most commonly-used metals for cylinder inserts).

NOTE: Cylinder inserts are sprayed with a protective coating in the factory to prevent corrosion during transit and storage. Individual cylinder inserts should be rinsed in acetone prior to use for optimal electrochemical results.

Part Number	Description
AFE9C150G064S1X-10	15 mm OD Cylinder Inserts, 1018 Carbon Steel, Pack of 10
AFE9C150G064T3X-10	15 mm OD Cylinder Inserts, 316/316L Stainless Steel, Pack of 10
AFE9C150G064T5X-10	15 mm OD Cylinder Inserts, 430 Stainless Steel, Pack of 10

Table 3. Commonly-Used 15 mm RCE Cylinder Inserts

4.4OpenTop Corrosion Cell

Between RCE experiments, users often want to clean the cell. This is sometimes difficult with standard glassware that features numerous glass joints and other such small openings. Pine Research has therefore designed OpenTop cells to go with 15 mm RCE corrosion bundles. The different OpenTop cells share the following features:

1 L volume
Fit PTFE OpenTop lid
Made of borosilicate glass
Designed specifically for the 15 mm RCE system shaft and MSR rotator

There are four styles of OpenTop cell, as follows:

Jacketed cell with drain valve (part number AFCELL8) OpenTop Cell with Water Jacket and Drain Valve
Jacketed cell without drain valve (part number AFCELL8U3) OpenTop Cell with Water Jacket
Basic (unjacketed) cell with drain valve (part number AFCELL8U) OpenTop Cell with Drain Valve
Basic (unjacketed) cell without drain valve (part number AFCELL8U2) OpenTop Cell

Often, a user wants to control the temperature of solution inside the cell. Users can select either a jacketed cell or a basic cell. By connecting a jacketed OpenTop cell to a circulating water bath, users can control the temperature of the internal solution. Threaded hose barbs are shipped with jacketed OpenTop cells. Alternatively, temperature in a basic, unjacketed cell can be controlled using a hot plate.

Some users want to drain the internal solution easily. Both the jacketed and basic, unjacketed cells can have a drain installed. If the drain is present, the OpenTop cell is shipped with a drain valve. The valve extends from the base of the OpenTop cell by about 3 in. For some users, this is undesirable, so they should select a cell without a drain. Each of the four styles of OpenTop cell will be shown in this section. Each 15 mm RCE bundle includes an OpenTop cell, which is one component of the AFCELL8* part number (where * = blank, U, U2, or U3, corresponding to the different cell configurations).

4.4.1Jacketed Cell with Drain Valve (AFCELL8)

The 1 L OpenTop corrosion cell that comes with AFCELL8 (part number RRPG122), included in the [RCE15-JV] and [RCE15-RJV] bundles, features a water jacket and drain (see Figure 11). Included with the water jacket and drain are the appropriate fittings (barbed hose connectors for the jacket and a threaded valve for the drain, see Figure 12).

Figure 11. OpenTop Jacketed Cell with Drain Valve (part number AFCELL8)

Figure 12. Threaded Barbed Hose Connectors and Drain Valve Stem with Knob

4.4.2Jacketed Cell without Drain Valve (AFCELL8U3)

The 1 L OpenTop corrosion cell that comes with AFCELL8U3 (part number RRPG210), included in the [RCE15-J] and [RCE15-RJ] bundles, features a water jacket (see Figure 13). Included with the water jacket are the appropriate fittings (barbed hose connectors for the jacket, see Figure 12).

Figure 13. OpenTop Jacketed Cell without Drain Valve (part number AFCELL8U3)

4.4.3Basic (Unjacketed) Cell with Drain Valve (AFCELL8U)

The 1 L OpenTop corrosion cell that comes with AFCELL8U (part number RRPG143), included in the [RCE15-V] and [RCE15-RV] bundles, is a basic, unjacketed cell (see Figure 14) with drain valve (see Figure 15) that integrates with the other components of the 15 mm RCE system.

Figure 14. OpenTop Basic (Unjacketed) Cell with Drain Valve (part number AFCELL8U)

Figure 15. Threaded Drain Valve Stem with Knob

4.4.4Basic (Unjacketed) Cell without Drain Valve (AFCELL8U2)

The 1 L OpenTop corrosion cell that comes with AFCELL8U2 (part number RRPG173), included in the [RCE15-X] and [RCE15-R] bundles, is a basic cell that integrates with the other components of the 15 mm RCE system (see Figure 16).

Figure 16. OpenTop Basic (Unjacketed) Cell without Drain Valve (part number AFCELL8U2)

4.5Accessories Included with 15 mm Corrosion Cell

As shown in Figure 3, each OpenTop RCE corrosion cell (AFCELL8*, part of each bundle in Table 1) comes with several accessories, each of which can be ordered individually as a supplement or replacement. The items included with the purchase of a 15 mm RCE product bundle, which includes AFCELL8*, has been provided in the tables below (see Table 4).

NOTE: Part numbers are given only for reference. Each part is already included in the cell when purchased as part of a bundle.

Part Number	Description	Quantity
AC01LID122	OpenTop Cell Lid, PTFE	1
AC01CLP1	Hoobler-Sagi Cell Clamps	3
AKCLAMP2	Ribbon Clamp and Cross Joint	1
AFCTR3	Graphite Counter Electrode Assembly	1
AFE9MBA	15 mm Single Cylinder RCE Shaft	1
AC01TPA6M	Gas-Purged Bearing Assembly	1
AC01APLUG	MutaPort Adapter, Plug	1
AC01A1420	MutaPort Adapter, 14/20 Port	1
AC01A2425	MutaPort Adapter, 24/25 Port	6
RRPG085K1	PTFE Stoppers, 24/25 Joint	7
RRPG031	Luggin Capillary (24/25 outside, 14/20 inside)	1
RRPG034	Dual-Port Purge/Sparge Accessory	1

Table 4. Accessories Included in 15 mm RCE Product Bundles (part of the AFCELL8* Cell Kits).

4.6Optional Accessories for 15 mm Corrosion Cell

Several accessories are available for the 15 mm corrosion setup. Each has been selected or designed to fit the OpenTop lid. As the cell kits in the 15 mm RCE product bundles contain several MutaPort adapters (see Table 4), the optional accessories fit into either a 14/20 or 24/25 port.

4.6.1Reference Electrodes

Reference electrodes are not included with any 15 mm RCE corrosion product bundles. This is intentional to allow the user to select their desired reference electrode since it may vary depending on the experimental conditions. Pine Research has several different options for standard size reference electrodes available.

A few important notes about Pine Research reference electrodes:

Standard size reference electrodes have a 9.5 mm OD body and come with a PTFE adapter that only fits into a 14/20 port
Standard size reference electrodes are compatible with the included Luggin capillary (part number RRPG031) Luggin Tube
Only two standard size reference electrodes can be shipped along with the other items in a 15 mm RCE corrosion product bundle: the Single Junction Ag/AgCl Reference Electrode (part number RREF0021) Single Junction Silver Chloride Reference Electrode and the Single Junction Non-Aqueous Ag Reference Electrode Kit (part number AKREF0033) Non-Aqueous Standard Reference Electrode Kit
All other standard size reference electrodes cannot be shipped together, and must necessarily ship separately. Additional shipping fees may also apply for any hazardous mercury-containing reference electrodes

There are three ways to introduce a reference electrode into a corrosion cell:

Directly, by inserting the reference electrode into the cell via a 14/20 port. This approach is most appropriate when the test solution is an electrolyte containing concentrated chloride salts (e.g., NaCl brine).
Semi-indirectly, by first inserting the Luggin tube (RRPG031) Luggin Tube through a 24/25 port, followed by insertion of the reference electrode into the inner chamber of the Luggin tube through its 14/20 port. The Luggin tube helps position the tip of the reference probe close to the cylinder insert. Close proximity between the reference and working electrode can reduce the potential shift that arises from uncompensated solution resistance between the reference electrode and the working electrode (RCE cylinder). Use of a Luggin tube becomes unnecessary when the test solution is highly conductive (i.e., having a high salt concentration) and the uncompensated resistance is low enough not to cause a significant measurement error in corrosion potential.
Indirectly, by a salt bridge (part number AKTUBE1420; Reference Electrode Salt Bridge Kit see next section for details on the salt bridge kit). One can use a salt bridge to physically and diffusionally isolate the reference electrode from the bulk solution. The salt bridge offers a conductive connection between the electrochemical cell (bulk solution) and a separate beaker of the same solution. A salt bridge may be an ideal accessory to use if a reference electrode becomes unstable. Reference electrode instability is often caused by a high solution temperature or by a chemical or physical process that plugs the frit at the tip of the reference electrode.

4.6.2Reference Electrode Salt Bridge Kit (AKTUBE1420)

As mentioned, the salt bridge offers an indirect manner by which to connect the reference electrode to solution in the electrochemical cell. Pine Research offers an easy-to-use salt bridge kit (part number AKTUBE1420) that users may wish to keep in the laboratory (see Figure 17).

Figure 17. Reference Electrode Salt Bridge Kit (part number AKTUBE1420)

4.6.3Condenser with 24/25 Joint (RRPG035)

A condenser (part number RRPG035) is an optional corrosion accessory useful for those who perform high temperature experiments (up to 80°C) where appreciable amounts of solvent may evaporate over the duration of a test. The condenser has an inner, spiral-shaped, high surface area tubing path for a cooling water stream that helps cool and condense hot solvent vapors as they rise from the solution, preventing large losses in the electrolyte volume over time (see Figure 18).

Figure 18. Corrosion Cell Condenser (part number RRPG035)

4.6.4Digital pH Probe with 24/25 PTFE Adapter (AKPH1)

Another optional accessory for the 15 mm RCE corrosion setup is a manual, digital pH probe for monitoring the solution pH actively during an experiment (part number AKPH1) (see Figure 19).

Figure 19. Digital pH Probe with 24/25 PTFE Adapter (part number AKPH1)

4.6.5Platinum Counter Electrode Assembly (AFCTR5)

Some users may prefer a platinum counter electrode (part number AFCTR5) (see Figure 20) over a graphite counter electrode (part number AFCTR3). In general, highly corrosive conditions over long periods of time may degrade platinum. The platinum counter electrode assembly comes with an isolation tube and PTFE adapter that only fits a 14/20 port, so the 14/20 MutaPort adapter must be used in the OpenTop cell lid.

The platinum counter electrode assembly comes with a fritted glass tube for isolation. The electrode can also be removed from the isolation tube and used directly in solution. In both configurations, a 14/20 port adapter is included.

Figure 20. Standard Platinum Counter Electrode Assembly with Fritted Isolation Tube (part number AFCTR5)

4.6.6Purge Kit for 1/4 Inch Tubing (AKPURGE1)

The purge kit (part number AKPURGE1) is useful to link a gas source (e.g., N₂ or Ar) to the dual port purge/sparge accessory (part number RRPG034) included in the 15 mm RCE product bundles (see Figure 21). The three way valve is useful in regulating flow through solution (bubbling, purging) or blanketing the headspace.

Figure 21. Purge Kit for 1/4 Inch Tubing, Including Three-Way Valve (part number AKPURGE1)

4.7Thermal Control Optional Accessories

Scientists studying flow-based corrosion analysis often want to control the temperature of the liquid in the cell. They may want to mimic the same conditions as in their corrosive system (e.g., hot crude oil in a pipeline) and temperature is a contributing physical parameter to corrosion rate.

Two OpenTop cell types are offered from Pine Research; those containing a water jacket for thermal control and those that are designed to heat directly on a hot plate without a water jacket. Use of a circulating water back in a cell water jacket provides a uniform temperature. However, it is not convenient to clean a jacketed cell after a test run because the cell is attached to the circulator with hoses. It may therefore be necessary for the researcher to determine which type of cell is most appropriate based on their priorities and the kinds of experimental parameters being studied.

4.7.1Manual Digital Thermometer with Glass Thermowell (AKTHERM1)

The simplest temperature-monitoring accessory for the 15 mm RCE corrosion setup is a manual, digital thermometer. This thermometer does not interface with an external data acquisition device (DAQ), and come with a glass thermowell and PTFE adapter that fits into a 24/25 port (part number AKTHERM1) (see Figure 22).

Figure 22. Manual Digital Thermometer with Glass Thermowell and 24/25 PTFE Adapter (part number AKTHERM1)

4.7.2Water Circulator Kits

Pine Research offers four different water circulator kits for use with jacketed electrochemical cells. The circulator maintains the temperature of a fluid reservoir at a setpoint of your choosing. The recommended circulating fluid is a viscous polymer solution (see product page on water circulator kits for further information). The fluid is circulated from the reservoir, out through hoses to the water jacket on the electrochemical cell, and then back to the reservoir. The temperature is typically monitored by a sensor located in the reservoir.

The four water circulator options are defined by their ability to either just heat, or both heat and cool, as well as the absence or presence of a "remote RTD sensor". For each option, there are also two individual part numbers corresponding to the different AC power options depending on the country of usage.

Heating only; temperature range +20°C to +100°C
- Part number AKAQUA22 (115 VAC, 60 Hz)
- Part number AKAQUA23 (230 VAC, 50 Hz)
Heating and cooling; temperature range -20°C to +100°C
- Part number AKAQUA32 (115 VAC, 60 Hz)
- Part number AKAQUA33 (230 VAC, 50 Hz)
Heating only; with RTD sensor; temperature range +20°C to +200°C
- Part number AKAQUA42 (110-115 VAC, 50-60 Hz)
- Part number AKAQUA43 (230 VAC, 50-60 Hz)
Heating and cooling; with RTD sensor; temperature range -20°C to +200°C
- Part number AKAQUA52 (115 VAC, 60 Hz)
- Part number AKAQUA53 (220 VAC, 50-60 Hz)

A point to consider is that each circulator kit includes a pair of chloroprene tubes (8 mm ID x 1.0 m long) and two pairs of hose clamps to facilitate connection to the hose barb connectors on a jacketed glass cell. Chloroprene tubing is rated for use between -20°C and +120°C. For temperatures above this range, tubing made of other materials must be used. However, it must also be noted that the highest temperature rating for most RCE products from Pine Research is only 80°C (due to the thermal limitations of PEEK), so for most RCE applications from Pine Research the chloroprene tubing should be sufficient.

There are several options, but the most ideal is likely the circulators with remote RTD sensors. The RTD sensor is PTFE-coated and may be placed inside the electrochemical cell directly to provide more direct control of the actual temperature in the cell (see Figures 23 through 26 for images of all water circulator options).

Figure 23. Water Circulator Kits, Heating Only (part numbers AKAQUA22/AKAQUA23)

Figure 24. Water Circulator Kits, Heating and Cooling (part numbers AKAQUA32/AKAQUA33)

Figure 25. Water Circulator Kits, Heating Only, with RTD Sensor (part numbers AKAQUA42/AKAQUA43)

Figure 26. Water Circulator Kits, Heating and Cooling, with RTD Sensor (part numbers AKAQUA52/AKAQUA53)

4.7.3Hotplate Kit with Thermocouple Feedback (AKHEATER1/AKHEATER2)

For users that prefer to heat the contents of their cell directly, they should choose a basic, unjacketed OpenTop cell. Heating with a hotplate tends to provide a non-uniform temperature gradient; however, the rotating shaft (with turbulent flow) will typically disrupt the temperature gradient and enhance the temperature gradient uniformity.

The hotplate is available in two electrical configurations: 110 VAC (AKHEATER1) and 220 VAC (AKHEATER2). The hotplate kit includes two 8” temperature probe thermocouples, a glass thermowell, and a 7 mm to 24/25 PTFE adapter (see Figure 27). Be sure to select the product whose electrical configuration is matched to the voltage source in your country. The hotplates have a ceramic top and maximum surface temperature of +300°C. It is recommended to use the included thermowell and add either water or high boiling point oil in order to achieve good thermal contact.


Code	Description
A	Digital Hotplate (in either 110 VAC or 220 VAC configurations) Hotplate Kits
B	PTFE-Coated Thermocouple Probe for Temperature Feedback (temperature limit is +190°C)
C	Glass Thermowell for Thermocouple Probe
D	Stainless Steel Thermocouple Probe for Temperature Feedback (temperature limit is +380°C)

Figure 27. Hotplate with Thermocouple Probe Feedback Sensors

The OpenTop cells are flat-bottomed and rest easily on the hotplate. The MSR Rotator base is large enough to accommodate our recommended hotplate with sufficient clearance above to install the cell and RCE accessories (see Figure 28).

Figure 28. Use of Hotplate and Thermocouple Feedback with AFCELL8U2 under MSR Rotator

The thermocouple connects to the rear of the hotplate, at the yellow two-prong (anode/cathode) connector (see Figure 29). By using the thermocouple feedback sensor probes in the electrochemical cell, the hotplate can more accurately control the temperature of the heating element relative to its setpoint and the actual solution temperature in the cell.

Figure 29. Connected Thermocouple to back of Hotplate

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