Scientific

Q: Everything you need to know about stability and uniformity

A: A thermostat controls the temperature of, for example, a water bath by measuring the temperature of the water and comparing it with the set temperature. It then adjusts the amount of heat put into the bath to make the measured temperature equal to the set temperature. Because there is a time delay between measuring the temperature and putting in the heat there will be a fluctuation in the temperature of the bath.

The heat is distributed in an unstirred bath by convection and conduction, and in a stirred bath by convection, conduction and the stirring action. The heat losses from the surface of the liquid and through the sides can also cause a change in temperature.

Due to the losses and distribution of heat there are small fluctuations in temperature across the bath.

The temperature fluctuation at any one point is called the stability, and the largest temperature difference between any two points in the bath is called the uniformity.

The temperature at any point varies regularly between two limits but occasionally a larger variation is observed. The stability as stated in DIN 58966 is the temperature difference between the maximum and minimum level over 100 cycles after removing the effect of the largest 25% of readings.

The stability is determined by measuring the temperature in the center of the working volume of the bath and is stated as plus or minus one half of the measured value.

The uniformity is determined by measuring the temperature in the center and corners of the bath and is the greatest difference between the mean temperatures at any of these points. It is stated as plus or minus half this value.

Q: What is Intelligent Control Optimisation™ “ICO”?

A: Intelligent Control Optimisation™ (ICO) is a control algorithm developed by Grant Instruments for use in the Optima™ range of immersion thermostats to automatically optimise the performance for liquid type and tank volume.

Most thermostatic controllers utilise proportional PI or PID temperature control, which is set up in the factory and fixed. ICO uses a heuristic real-time adaptive PID control; in this case the proportional control parameters are adjusted as the controller heats up and stabilises. Based on the heat-up rate, the load and volume of liquid are calculated and an assessment made of liquid type; the control algorithm is then adjusted accordingly. The benefit to the user is that the controller applies the optimum control algorithm for any given situation. This is a feature not available on competitive products, as the fixed control is always a compromise.

ICO offers additional safety for users working with oil, as excessive localised heating at the heater element is prevented, and cracking avoided; cracking oil can produce toxic fumes and may present a potential fire hazard.

With Labwise™ software it is possible to see the control adapting in real time on the status display, as the controller heats up and locks onto the desired temperature.

Q: Which water should you use in your bath?

A: For the long-term reliability of water baths it is important to use oxygenated water that is free from ions and minerals that can cause corrosion of stainless steel. We recommend the use of distilled water and de-ionised water from modern ion exchange systems that do not use salt back flushing to regenerate the ion-exchange cartridges.

Stainless steel is protected from corrosion by a layer of chromium oxide. If the layer is damaged oxygen present in water can reform the oxide layer. If the water is still or de-oxygenated and the oxide layer is damaged, ions can corrode the stainless steel tank. If a water bath has been unused for some time, or water boiled, we recommend changing for fresh distilled water or correct de-ionised water.

Water normally contains calcium or magnesium ions. De-ionised water has most ions removed as indicated by its conductivity level; the purer the water the lower the conductivity. It is important to use only de-ionised water from an ion exchange system with replaceable cartridges. Do not use de-ionised water generated from an ion-exchange system that incorporates a salt back-flush system to regenerate the ion-exchange resin as this can leave sodium ions that are very corrosive to stainless steel.

Q: How to prevent rust in water baths

A: Most Grant tanks, as well as immersed parts, are made from type 304 stainless steel, an extremely versatile general purpose grade of stainless steel. It is the excellent forming characteristic that has made this grade dominant in the manufacture of laboratory and industrial water baths, as well as domestic sinks and saucepans. Type 304 stainless steel is highly suitable for applications where hygiene is important; it exhibits good heat resistance and excellent resistance to corrosion.

However, despite resistance to general surface corrosion, stainless steel is susceptible to specific types of corrosion, in particular pitting (small pin hole style corrosion) and stress corrosion cracking. It can also undergo general corrosion in specific environments, such as one containing hydrochloric or sulphuric acids.

Stainless steel is protected by its high content of alloying elements, primarily chromium and nickel. Chromium is the most important with respect to corrosion resistance, although the nickel assists in allowing the chromium to do its job. The chromium forms an oxide layer on the surface of the steel, which inhibits further oxidation. This layer adheres extremely well to the metal substrate, but it is essential that it remains intact, and must be protected from various forms of damage.

If the surface chromium oxide layer becomes damaged, oxygen present in water can partially reform the oxide layer, so it is advisable to ensure that water is always fresh and well oxygenated. Baths that will be out of use for an extended period should be emptied, and all moisture should be wiped from the bottom of the tank.

In some cases a brown layer may appear on the surface of a stainless steel tank. In most of these cases this is not rust, but it may be a surface deposit of minerals from the local water supply, or ferrous particles or salts that have fallen into the tank. These surface deposits can often be removed by using a household cleaner such as Duraglit or Silvo metal polish.

Q: How to prevent algae and bacteria?

A: Water baths provide the ideal environment for the growth of micro-organisms. If left uncontrolled the growth of these organisms can result in a range of serious problems and health risks from pathogenic bacteria.

The growth of algae on the surface of parts will cause biofouling which will reduce performance.

Micro-organisms that produce acidic metabolic by-products can cause bio-corrosion by depolarisation of metal surfaces.

There are a number of biocides available on the market.

Q: How to clean your stainless steel tank, accessories and heater elements?

A: The cleaning of the stainless steel is important to maintain a good corrosion free finish. Stainless steel is easy to clean, washing with soap or mild detergent and warm water followed by a clear water rinse typically being adequate. Where stainless steel has become extremely dirty with signs of surface discolouration (perhaps following a period of neglect or misuse) then the following alternative methods of cleaning can be used.

Q: Overtemperature cut-out operation

A: Many Grant temperature control products feature an adjustable overtemperature cut-out. This safety feature may be valuable to the user in a variety of ways:

• protection of delicate or expensive samples, where too high a temperature would cause irreparable damage
• protection in the use of hazardous chemicals, by preventing the flashpoint from being exceeded
• protection in the use of a remote probe – e.g., you have a tank of water heated by heat-exchange coil, controlled at 50°C by a remote probe; if the remote probe should become dislodged, the cut-out set at 60°C would prevent the temperature controller continuing to heat ad infinitum

The overtemperature cut-out cannot be set to a specific temperature. It is a manual device, separate from the temperature control electronics, in accordance with IEC61010. There are two methods of setting the overtemperature cut out:

Option 1 (quick method)

Set the temperature to the required value and leave the bath to stabilise for a least 5 minutes after the set point has been reached. Turn the control slowly anticlockwise, using a screwdriver, until the alarm lamp comes on. Press the reset and at the same time turn the control slowly clockwise until the alarm lamp goes out. This gives an overtemperature trip point of approximately 10 to 30 °C above set temperature.

Option 2 (precision method)

Set the temperature to the cut-out level required and leave the bath to stabilise for a least 5 minutes after the set point has been reached. Turn the control slowly anti-clockwise, using a screwdriver, until the alarm lamp comes on. Allow the bath to cool, then press the reset button and the unit will start. (The bath will have to cool by 15 to 30º before the reset will work). This gives an overtemperature trip point of the set value. Now decrease the set temperature to the working set point.

Please note that products are dispatched from Grant with the cut-out set at minimum in order to prevent any accidents before the equipment has been properly set up. Depending on the operating temperature required, the cut-out should initially be adjusted to mid-way, or even maximum, to allow the set temperature to stabilise.

Q: How to calculate the heat up time in a Grant water bath?

A: The heat up time for any Grant water bath can be determined from the volume of liquid, the heater power, the temperature difference and the heat capacity of the circulation systems. A simple formula is used to calculate the heating time in the system.

t = V x Δ T x K
60 x W where:

t = Heating time (minutes)
V = Total liquid volume (litres L)
ΔT = Temperature difference (ºC)
K = Liquid heat capacity (J/L/ºC)
For water: K = 4200
For silicone oil: K = 1680
W = Heating power (Watt)

Example: A 12 litre bath containing water with a thermostat of 1400 W heating capacity can raise the temperature from +20ºC to +56ºC in 21.6 mins.

t = 12 x (56 -20) x 4200 = 21.6 mins
60 x 1400

Q: How to calculate the cool down time in a Grant low temperature circulator?

A: The cool down time can be calculated by using the same formula as above.

t = V x ΔT x K
60 x W

However, as the temperature decreases the cooling power of the circulator reduces, it is therefore necessary to estimate the average cooling power across the temperature range to be cooled.

Cooling power Watts = Cooling power at lower temperature + Cooling power at upper temperature/2

An example: For a 6 litre cooling bath with a cooling power of 1000W at +20°C and 500W at 5°C using water, the cool down time from +20°C to 5°C will be:

t = 6 x 15 x 4200 = 8.4 mins
60 x (1000+500)/2

Q: Everything you need to know about Grant Pumps Part 1

A: In Grant water baths and circulators the pump is used only to circulate liquid to an external device, not for stirring within the tank. An independent stirrer is used for circulation within the tank, in order to achieve optimum temperature uniformity throughout the working area.

Pump performance is specified in terms of flow rate and pressure. The flow is normally quoted in litres/min. Pressure can be quoted in mbar, metres (of water) head and psi (pounds per square inch).

The relationship between pressures is:-

One atmosphere is 1010 mbar, 10.3 metres of water or 14.6 psi

In accordance with DIN58966 part 1, maximum flow is measured into an open vessel, through a horizontal pipe attached to the pump outlet; the pipe must be at least 0.5 m in length.

The maximum pressure is determined from the maximum height to which water can be pushed in a vertical tube connected to the pump output. The head is measured in metres of water.

The measurements described above are maximum flow, which is at zero head, and maximum pressure which is at zero flow. Neither of these conditions is likely to be met in practice. In practical terms, when a pump is connected to an external device, the actual flow rate is determined by the bore (diameter) of the pipe, and any friction in the pipes. Any kink or change in diameter in the pipe will cause a reduction in flow rate.

To achieve maximum flow rate:

• use large bore (diameter) pipes
• avoid changes in bore size within the circuit
• ensure all interconnecting joints are smooth
• position pipes such that curves are smooth

The flow rate through the circuit can be adjusted by, for example, installing an in-line tap. If the flow rate is too low, check that:

• there are no foreign objects obstructing the flow through the pipe
• the bore is as large as possible
• the pipes are as short as possible
• there are no kinks or tight bends

Ultrasonic Bath

Q: What detergents should I use in my ultrasonic cleaner?

A: This will vary depending on your application.

Medical devices should be cleaned using a pH neutral detergent. Industrial cleaning can incorporate more alkali or in some cases more acidic detergents. Special consideration should be made when cleaning aluminium or other soft metals which are more susceptible to pitting when subjected to ultrasonic cavitation.

For information on which detergent you require for your cleaning process please contact Grant.

Q: How long do I need to clean my components for?

A: Cleaning time varies depending on the performance of your ultrasonic bath and the level of contamination present. Different conditions (temperature, ultrasonic power, detergent and detergent dose) will all have an effect on the length of time required to clean a component.

Q: How much can I load into my ultrasonic cleaner?

A: The more instruments placed into an ultrasonic bath, the less effective the cleaning cycle is going to be. It is not advisable to place instruments in the basket so that they overlap as a more effective clean will be generated if all surface areas are openly exposed to the cleaning solution. However, filling a basket so that there is clear space between instruments should lead to an effective cleaning cycle.

Q: What service options are available for my ultrasonic cleaner?

A: Grant Instruments can provide tailored service contracts to suit your specific needs. For more information on the options available, please contact the Grant service department on +44 (0) 1763 260 811 or e-mail service@grant.co.uk

Q: Why do I need to degas my ultrasonic cleaner before use?

A: Gases are present in tap water. To allow optimum ultrasonic activity to occur within the bath these gases need to be removed. Activating the ultrasonics, prior to initiating a cleaning cycle will remove these gases from the fluid.

The period taken to degas the fluid can vary depending on the size of the bath and the hardness of the water.

Q: How often do I need to change the cleaning solution?

A: This will vary depending on the cleaning application and the frequency with which the bath is used.

When cleaning medical instruments, it is recommended that new solution is added to the bath twice a day – based on an 8 hour day i.e. once every 4 hours.

Depending on the convenience and application, industrial ultrasonic tanks may require a fluid change more or less regularly. The cleaning results and fluid in the bath should be monitored for contamination after cleaning and judgment made by the operator on how often the fluid needs to be changed. Please contact Grant for guidance on this.

Q: Can I remove items from the ultrasonic tank while it is in operation?

A: Items should not be removed from the bath during a cycle. To ensure the cleaning process is complete, items should remain in the bath until the cycle has completed.

Placing hands in the ultrasonic bath while running a cycle should also be avoided.

Q: Should the lid be on my ultrasonic cleaner when in operation?

A: The lid should be kept on the ultrasonic cleaner while in operation.

The lid is for the protection of the operator and in medical applications the patients also. It prevents aerosols generated during the cavitation process from dispersing and contaminating the reprocessing environment. In addition, the lid reduces the noise levels created during the ultrasonic cycle and helps to maintain the heat of the cleaning fluid in the tank.

Q: How can I test the level of ultrasonic activity within the bath?

A: There are a number of recommended tests for establishing levels of ultrasonic activity in the bath.

The foil test involves suspending a strip of foil into various locations around the tank. The foil should not touch the base of the tank and should be held in position for around 1 minute. It should then be removed and there should be an even distribution of perforations and small holes on the surface of the foil.

Another test requires the use of Brownes soil test strips. These are plastic strips which have been contaminated to simulate the contamination which might affect surgical instruments. After running an ultrasonic cycle the strips should be taken from the bath and all contamination should have been removed.

An ultrasonic energy meter can also be used to test the level of ultrasonic activity within the tank.

Please contact Grant for more information on ultrasonic activity testing methods.

Q: Why do I need to use a basket in my ultrasonic bath?

A: A basket should be used in order to protect the base of the ultrasonic tanks from damage.

Placing items directly into the tank so that they are in contact with the base can cause damage to the bath. When instruments are in direct contact with the bath, the action of generating ultrasonic activity can cause excessive wear to the base of the tank. Using a Grant ultrasonic bath without a basket will invalidate your warranty.

Items should be placed in a stainless steel, mesh basket so that the ultrasonic activity is not significantly reduced.

2020 and 2040 FAQs

Q: Battery and Power

A: How long will the batteries last in the 2020/240 Logger?

With all channels logging, the following table can be used as a guide: -

LOGGING INTERVAL
1F8
2F8/2F16
4F16

What happens when the batteries are exhausted?

It is not possible to arm the logger when below approximately 5.5. Volts. If the unit was logging when the voltage dropped below this point, it will disarm automatically.

Can I power from an external supply?

Yes, 10-18V DC only. Includes 12V DC battery. What happens if the external supply fails? If the external power fails, batteries must be fitted to prevent loss of data. In the case of a power failure, the logger will switch to the battery supply and continue with no interruption.

How is the battery level displayed?

By use of a “bar” multi-segment battery indicator on the logger display and, if required, the actual voltage is displayed in the appropriate screen both on the logger display and in SquirrelView.

Can the 20xx Logger be used on a vehicle?

The logger is designed to be powered from a 12V vehicle system directly, higher system voltages will require the use of a suitable convertor. Two high voltage inputs are available to directly monitor vehicle supplies (up to 60V).

Can the Logger be powered by the USB port?

No. However, the use of USB does not put any extra load on the logger power supply or batteries.

How do I power a GSM modem?

A power adaptor lead is included with the GSM kit (SQ20A802) to power the modem and the Squirrel from the mains power pack (MPU-12V)

Can I power sensors from the Logger?

Yes via connection terminal EA external supply (as supplied into the DC power socket Max 100mA B 5V regulated output Max 50mA

Can the internal batteries be rechargeable?

No only AA alkaline batteries should be used.

Q: Connections and Communications

A: Is the Logger USB 2.0 Compliant?

Yes

Can I connect to the logger remotely?

Yes via 3rd party Ethernet or wireless adapters as well GSM and dial-up modem.

Contact Grant Instruments or your distributor for more details.

Is the logger real ‘plug & play’ via USB?

Windows will automatically detect the presence of your data logger, supplied drivers will be required the first time used.

What if I connect to both ports simultaneously?

The USB and serial ports may be physically connected at the same time; however, the logger will talk to only one external host at a time.

Can the logger survive mains supply accidentally connected to inputs?

The unit is not designed to withstand such an event; however the unit is ESD protected.

Can the Logger connect to Ethernet?

Yes the SQ2020 2F8, SQ2040 2F16 and the SQ2040 4F16 have inbuilt Ethernet connection. For the SQ2020 1F8 we supply a serial RS232, Ethernet converter kit (SQ20A801) a power adaptor lead is included with the kit to power the modem and the Squirrel from the mains power pack (MPU-12V)

Q: Operation

A: Can I download while the logger is logging?

Yes if downloaded via SquirrelView, but not to MMC. The logger will download until the point that the instruction to download was issued.

Can I download by time?

Yes, use the advanced function in the download screen.

What is the alarm output regime (one per channel)?

User specified triggers can activate a total of 4 alarm outputs. As an example; these triggers may be based upon channel conditions.

What can I trigger from?

Triggers can be from analogue, digital channels or time.

Can I print direct from the logger?

No, this can only be achieved via the host

Can I set an automatic download?

Yes Downloader is supplied on the SquirrelView CD

Why is the Ref Junction set automatically when I select a Thermocouple in Sensor Type?

Thermocouples do not measure absolute temperature, they only measure the temperature difference between the sensing end (the probe tip) and the reference end (where the probe plugs into the logger). To acquire the absolute temperature the logger adds together the temperature difference measured by the thermocouple to the temperature at the reference junction. The reference junction temperature is measured by the Reference Junction channel. To save the user from having to remember to turn on the Reference Junction channel, SquirrelView and the logger do it automatically whenever a thermocouple channel is selected.

Can I use the logger outside?

The logger is not weatherproof if to be used outside or in damp conditions it will need to be placed in an IP rated enclosure

Q: General

A: Can I read my data using notepad (.csv file)?

By using SquirrelView you are able to export data to .csv format to a preferred spread sheet.

Can I fit the logger to a wall?

Yes, a universal bracket is supplied as standard with each Logger. It can be adjusted to act as a wall bracket or desk stand.

How often does the Logger require calibration?

Drift is not expected although annual calibration is recommended. In real terms this is dependant upon use. Contact Grant Instruments for further details. The last date of calibration can be viewed via SquirrelView->Diagnostics->20xx logger

What is the Inter-channel isolation?

For 1F8 loggers, inputs on blocks A to D share a common measurement circuit and must be within ±25V of each other and within ±60V of the negative pin on the logger’s power supply.

For 2F8 loggers, inputs on blocks A and B share one measurement circuit and blocks C and D share another measurement circuit. Inputs on blocks A and B must be within ±25V of each other and within ±60V of the negative pin on the logger’s power supply. Inputs on blocks C and D must be within ±25V of each other and within ±60V of the negative pin on the logger’s power supply. Inputs on blocks A and B must be within ±60V of the inputs on blocks C and D.

For 2F16 loggers, inputs on blocks A to D share one measurement circuit and blocks G to K share another measurement circuit. Inputs on blocks A to D must be within ±25V of each other and within ±60V of the negative pin on the logger’s power supply. Inputs on blocks G to K must be within ±25V of each other and within ±60V of the negative pin on the logger’s power supply. Inputs on blocks A to D must be within ±60V of the inputs on blocks G to K.

For 4F16 loggers, there are four separate measurement circuits connected to four pairs of input blocks – A and B, C and D, G and H, and J and K. Inputs on each pair of blocks must be within ±25V of each other and within ±60V of the negative pin on the logger’s power supply. Any input on any block pair must also be within ±60V of any other input on any other block pair.

Caution: Voltages approaching 60V and above can cause personal injury.

Q: Memory

A: How long will the memory last?

How long the memory will last is mainly dependant upon the number of channels set and their sample rate. For sample rates that are not sub-hertz, 16 bytes are used per reading (less than 16 bytes is used when logging sub-hertz). If Channel 1 was logging every second it would take approximately 11 days to fill the internal capacity or 16 weeks if logging every 10 seconds. If 4 channels log every 10 seconds the memory would fill in approximately 40 days.

The table below can be taken as a guide for a logger set to the default memory size of 16Mb.

If I install a external memory card, will it increase the memory?

No, the memory card is used to download your data without the need for a PC.

What happens when the memory is full?

The logger will disarm and go into the memory full condition. The logger cannot be armed again until enough free space is made available by the deletion of data. Download and most other functions will still be available when memory is full.

Can I choose how much memory to download?

It is not possible to specify memory but it is possible to download between two specified times.

Do I need to use a specific brand of memory card?

If you experiencing compatibility problems with a MMC/SD card, ensure that the logger controller firmware is at version 2.2 or above (firmware upgrades are included in you SquirrelView installation directory).

Do you recommend a specific brand of memory card reader?

Any brand name should work without issue but SANDISK or Microtech Zio are two known good readers.

Can I program the logger from a memory card?

Yes, in that setups created in SquirrelView can be saved onto a card and loaded into the logger using the stored setups menu.

Q: Speed

A: How fast can I log with n number of channels?

See Sample Rates under 2020/40 Squirrel

Can I have different channels logging at different speeds?

Yes, a total of 4 sample intervals can be specified, but they must be multiples of each other.

Q: Front Panel Controls for new SQ2020/2040 range with 128*64 dot graphical LCD

A: How many Channels can I view on the logger display at the same time?

In the meter mode 3 channels are displayed on the screen at one time and others can be viewed by using the up and down arrows.

How many channels can I view on the graph display at the same time?

Only one channel can be viewed on the graph, and this is chosen from the meter mode.

Can I display sampled inputs in real time?

The metering feature allows data to be viewed on the logger display or SquirrelView at approximately 1Hz, regardless of channel sample rates.

Can you lock and disable the keypad?

You can configure the logger such that no changes to setup can be made (read only). Refer to the Configuration Tab in SquirrelView Logger Setup.

Can I program the logger from the front panel?

Yes you are able to configure channels using the front panel buttons as well as being able to load pre-configured setups that have previously been stored in the logger.

Can I start logging from the front panel keypad?

Yes the logger can be armed and disarmed from the front keypad.

Q: Front Panel Controls for the old range of SQ2020 and SQ2040 ranges (models released before March 2011)

A: How many channels can I view on the loggers display at the same time?

One channel at a time by using the metering feature, with auto scroll of all channels if required (press and hold enter key).

Can I display sampled inputs in real time?

The metering feature allows data to be viewed on the logger display or SquirrelView at approximately 1Hz, regardless of channel sample rates.

Can you lock and disable the keypad?

You can configure the logger such that no changes to setup can be made (read only). Refer to the Configuration Tab in SquirrelView Logger Setup.

Can I program the Logger from front panel?

You may load pre-configured set-ups that have previously been stored in the logger, or from the External Memory Card

Can I start logging from the front panel keypad?

Yes, the logger can be armed and disarmed from the front panel keypad.

Grant Bio FAQs

Q: Why does my Centrifuge LMC3000/LMC4200R indicate ‘IMBALANCE’?

A: If the rotor becomes imbalance this causes vibration and the centrifuge will stop automatically. After the rotor has stopped open the lid and remedy the cause of the imbalance, this could be due to the tubes not being arranged symmetrically. Rearrange the tubes so that they are symmetrical (facing one another), and that opposite tubes are filled equally.

Q: What refrigerant is used for cooling the LMC-4200R?

A: #R134A; 250g

Q: Why does my Thermoshaker PCMT make a rattling noise when it is unpacked or moved?

A: The automatic balancing system produces a light metal-like noise when moving the unit, it is a normal occurrence and does not indicate a fault.

Q: Why does my Thermoshaker PCMT/PHMT appear to be not heating/cooling?

A: It could be possible that the plug connecting the unit and the heater/cooler block has become dislodged. To check this is connected correctly, disconnect the external power, remove the four knurled screws holding the block in place. Make sure that the plug is connected securely between the block and the unit. Align the block so that the warning label is facing the front of the unit and secure using the four knurled screws.

Q: Why does my Orbital Platform Shaker PSU-10i/PSU-20i/PCMT and PHMT have a friction sound at the beginning and the end of a cycle?

A: This is automatic loading balancing system adjusting itself for the operation, it is a normal occurrence and does not indicate a fault.

Q: On my PHMP/PHMP-4 how is the displayed temperature calculated?

A: There are two heaters in the PHMP/PHMP-4 microplate shaker, a bottom heater and the lid heater. The temperature on the lid heater will be a few degrees higher than than that of the bottom heater, this helps to prevent condensation in the microplates.

The temperature of the lid is calculated as follows:
For the temperature greater than 30 degrees, t(lid)=t(set)/16+t(set)

The actual temperature on the display is shown as the temperature of the bottom heater, actually when you set the temperature, you set the temperature on the bottom and the lid heater temperature is regulated by the program.
If one of the heaters is not working, then the actual temperature on the display will be empty. There is no special alert or sound signal to inform you that the heating is ON, but temperature will not be increasing.

Q: Can my PCH-1 be used in an hydrogen/nitrogen atmosphere?

A: No it is not recommended for the PCH-1 to be used in an hydrogen/nitrogen atmosphere, it can cause condensation inside the instrument and this along with the environment conditions will cause the unit to fail.

Q: What is the airflow rate for my UV cabinett?

A: The single fan air recirculation achieves around 7m³/h

Q: What is the power consumption of my UV cabinet?

A: The power consumption of the UV cabinets are as follows:

UVC/T-M-AR  67W

UVT-B-AR    67W

UVT-S-AR    150W

Q: How many hours will the UV lamps operate before degradation in my UV cabient?

A: The UV lamps (TUV) will operate for approximatley 8000 hours before degradation, once the lifetime has been reached the output will degrade quickly over a short period of time.

Unstirred Water Bath FAQs

Q: Unstirred Water Bath FAQs Which water should you use in your bath?

A: For the long-term reliability of water baths it is important to use oxygenated water that is free from ions and minerals that can cause corrosion of stainless steel. We recommend the use of distilled water and de-ionised water from modern ion exchange systems that do not use salt back flushing to regenerate the ion-exchange cartridges.

Stainless steel is protected from corrosion by a layer of chromium oxide. If the layer is damaged oxygen present in water can reform the oxide layer. If the water is still or de-oxygenated and the oxide layer is damaged, ions can corrode the stainless steel tank. If a water bath has been unused for some time, or water boiled, we recommend changing for fresh distilled water or correct de-ionised water.

Water normally contains calcium or magnesium ions. De-ionised water has most ions removed as indicated by its conductivity level; the purer the water the lower the conductivity. It is important to use only de-ionised water from an ion exchange system with replaceable cartridges. Do not use de-ionised water generated from an ion-exchange system that incorporates a salt back-flush system to regenerate the ion-exchange resin as this can leave sodium ions that are very corrosive to stainless steel.

Q: How to prevent rust in water baths

A: Most Grant tanks, as well as immersed parts, are made from type 304 stainless steel, an extremely versatile general purpose grade of stainless steel. It is the excellent forming characteristic that has made this grade dominant in the manufacture of laboratory and industrial water baths, as well as domestic sinks and saucepans. Type 304 stainless steel is highly suitable for applications where hygiene is important; it exhibits good heat resistance and excellent resistance to corrosion.

However, despite resistance to general surface corrosion, stainless steel is susceptible to specific types of corrosion, in particular pitting (small pin hole style corrosion) and stress corrosion cracking. It can also undergo general corrosion in specific environments, such as one containing hydrochloric or sulphuric acids.

Stainless steel is protected by its high content of alloying elements, primarily chromium and nickel. Chromium is the most important with respect to corrosion resistance, although the nickel assists in allowing the chromium to do its job. The chromium forms an oxide layer on the surface of the steel, which inhibits further oxidation. This layer adheres extremely well to the metal substrate, but it is essential that it remains intact, and must be protected from various forms of damage.

If the surface chromium oxide layer becomes damaged, oxygen present in water can partially reform the oxide layer, so it is advisable to ensure that water is always fresh and well oxygenated. Baths that will be out of use for an extended period should be emptied, and all moisture should be wiped from the bottom of the tank.

In some cases a brown layer may appear on the surface of a stainless steel tank. In most of these cases this is not rust, but it may be a surface deposit of minerals from the local water supply, or ferrous particles or salts that have fallen into the tank. These surface deposits can often be removed by using a household cleaner such as Duraglit or Silvo metal polish.

Q: How to prevent algae and bacteria

A: Water baths provide the ideal environment for the growth of micro-organisms. If left uncontrolled the growth of these organisms can result in a range of serious problems and health risks from pathogenic bacteria.

The growth of algae on the surface of parts will cause biofouling which will reduce performance.

Micro-organisms that produce acidic metabolic by-products can cause bio-corrosion by depolarisation of metal surfaces.

There are a number of biocides available on the market.

Q: How do I clean the stainless steel tank and accessories?

A: The cleaning of the stainless steel is important to maintain a good corrosion free finish. Stainless steel is easy to clean, washing with soap or mild detergent and warm water followed by a clear water rinse typically being adequate. Where stainless steel has become extremely dirty with signs of surface discolouration (perhaps following a period of neglect or misuse) then the following alternative methods of cleaning can be used.

Q: Setting the sample protection thermostat JB Aqua Plus

A: The bath is fitted with an adjustable sample protection thermostat to protect the sample. This device is not a safety feature. The sample protection thermostat can be set to be a few degrees above the bath set temperature.

1. Wait for the bath to stabilise at the correct temperature (can be checked with external thermometer if needed).
2. Turn the sample protection thermostat control knob slowly anti-clockwise until an audible “click” is heard (and the heater lamp goes off if it was on) and then turn it clockwise until another audible “click” is heard.

In the unlikely event of failure of the primary temperature control system, the sample protection thermostat will maintain the water in the bath at a temperature a few degrees above the control temperature. This will be indicated by the two orange lamps cycling on and off. If this happens, first check that the sample protection thermostat is not set to a lower temperature than the primary control system. If that is not the reason, the main control thermostat is not operating correctly. The bath can continue to be used without compromising the safety of persons or the surroundings until current work is completed. However, it is recommended to have the bath checked by a competent person as soon as conveniently possible.

Q: Setting the Sample protection thermostat SUB Aqua Plus

A: The bath is fitted with an adjustable sample protection thermostat to protect the sample. This device is not a safety feature. The sample protection thermostat can be set to be a few degrees above the bath set temperature.

Turn the knob of the sample protection thermostat to maximum.
Set the control temperature to 2°C above the desired operating temperature and wait for the temperature to stabilise.
Turn the knob of the sample protection thermostat slowly anti-clockwise until a click is heard and “Otc” is displayed. The audible alarm will sound continuously to warn you that the bath is controlling using the sample protection thermostat.
Re-set the control temperature to the desired temperature using the “+” and “-” keys. The audible alarm will sound continuously until the primary control system is re-activated.
In the unlikely event of failure of the primary temperature control system, the sample protection thermostat will maintain the water in the bath at a temperature a few degrees above the set temperature and with greater fluctuations. The display will cycle between “Otc” and the actual bath temperature and the audible alarm will sound intermittently. If this happens, first check that the sample protection thermostat is not set to a lower temperature than the primary control system. If that is not the reason, the bath can continue to be used without compromising the safety of persons or the surroundings until current work is completed. However, it is recommended to have the bath checked by a competent person as soon as conveniently possible.

Q: Resetting the over temperature cut-out SBB Aqua Plus

A: Two fixed over temperature cut-outs prevent the heater from overheating in the case of a low water level. The reset buttons for the over temperature cut-outs are on the side panel and can be reset by removing the protective black cap and pressing the red button in.

The over temperature cut-outs may activate during normal operation. If this is the case then they can be reset and the bath can continue to be used without compromising the safety of persons or the surroundings. However, if the cut-outs are persistently activated then it is recommended to have the bath checked by a competent person as soon as possible.

Refrigeration FAQs

Q: How do I calculate the cool down time of a Grant low temperature circulator?

A: The cool down time can be calculated by using the same formula as above.

t = V x ΔT x K
60 x W

However, as the temperature decreases the cooling power of the circulator reduces, it is therefore necessary to estimate the average cooling power across the temperature range to be cooled.

Cooling power Watts = Cooling power at lower temperature + Cooling power at upper temperature/2

An example: For a 6 litre cooling bath with a cooling power of 1000W at +20°C and 500W at 5°C using water, the cool down time from +20°C to 5°C will be:

t = 6 x 15 x 4200 = 8.4 mins
60 x (1000+500)/2

Q: What is the refrigerant type and charge used in my refrigeration unit?

A: