Grant LTC2 User Manual

Low temperature
circulator

LTC2

Operating Manual

Grant Instruments, based near Cambridge, England is a world leader in the
manufacture and design of equipment for sample preparation, scientific analysis, data
acquisition and data analysis providing solutions to the global scientific and industrial
markets.

Standards Compliance and Quality

Grants’ brand and reputation are based around quality, reliability and accuracy. We
ensure our products stringently meet all necessary international safety standards.
We pay particular attention to the safety testing of products and remain at the forefront of
the product safety standard for laboratory equipment IEC 61010-1. The company is
committed to operating its safety test laboratory in accordance with the requirements of
ISO 17025.

Grant operates a Quality Management System that complies with the requirements of BS
EN ISO 9001:2008.

Beyond compliance to the standard, Grant is committed to continually improving in
everything we do; with particular emphasis on understanding what matters to our
customers and suppliers, and designing our systems and work to meet their needs.

If you have any feedback on Grant’s products or services we would like to hear from you.
Please send all feedback to:

Quality Manager
Grant Instruments (Cambridge) Ltd
Shepreth
Cambridgeshire
SG8 6GB
UK

Tel: [phone]
Fax: [phone]
E-mail: [e-mail]

Contents

Contents 2

1.0 Use of products 4

2.0 How to use this operating manual 4

3.0 Safety information 4

3.1 Safety compliance 4

3.2 Safety symbols 4

3.3 Safety warnings 5

4.0 Operating instructions 6

4.1 Unpacking instructions 6

4.2 Recommended liquids 6

4.3 Installation 7

4.4 Electrical supply 7

5.0 Operating procedures 8

5.1 Operation 8

5.1.1 Liquid level 8

5.1.2 Operation above 60°C 8

5.1.3 Using the pump 8

5.1.4 Emptying the LTC2 9

5.1.5 Setting up and switching on 9

5.2 Using the LTC2 10

5.2.1 Product description, control unit 10

5.2.2 Control unit product indicators 10

5.2.3 Product description, refrigeration unit front panel (grille removed) 11

5.2.4 Product description, refrigeration unit rear panel 12

5.2.5 Setting the control temperature 12

5.2.6 Selecting liquid type 12

5.2.7 Setting the over-temperature thermostat 13

5.2.8 Configuring a preset 13

5.2.9 Running a bath preset 14

5.2.10 Completing a calibration 14

5.2.11 Restoring factory calibration settings 15

5.2.12 Adjusting display brightness 15

5.2.13 Setting a countdown timer 15

5.2.14 Cancelling the timer 16

5.2.15 Setting a high temperature warning alarm 16

6.0 Technical specifications 17

6.1 Operating conditions 17

6.2 Electrical details 17

6.3 Performance 17

7.0 Technical Tips 18

7.1 Which water should you use in your bath? 18

7.2 How to prevent rust in water baths 18

7.3 How to prevent algae and bacteria? 19

8.0 Warranty information 19

9.0 Maintenance and service 19

9.1 Routine maintenance 19

9.2 Cleaning 19

9.3 Fuses 20

9.5 Routine safety tests 20

9.6 Service 21

10.0 Optional accessories 21

10.1 Alternative pump 21

11.0 Troubleshooting 22

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12.0 Contact Grant Instruments 24

13.0 Compliance 24
Notes 25

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1.0 Use of products

Caution: Surfaces and heat transfer liquid can be hot during and after use.

Read this manual before using the bath.

Important safety warning.

The following products are covered by this operating manual:

 LTC2 & LTC2L

The products listed above are low temperature circulators designed for indoor laboratory
use by a professional user.

The LTC2 consists of a TC120 immersion thermostat combined with an R2 refrigeration
unit, with insulated hoses and clips to allow circulation of temperature control fluids to
external equipment.

2.0 How to use this operating manual

This operating manual will allow you to unpack, set-up and operate this low temperature
bath/circulator correctly and safely. Important safety information, symbols and warnings
are listed below and should be read carefully. Section 4 gives information about how to
unpack and install the product correctly. Section 5 gives operating information for the
LTC2. Product technical specifications and tips are provided in sections 6 and 7. The
warranty for this product is for FOUR YEARS and is detailed in section 8 and should be
registered by completing the on-line registration form at www.grantinstruments.com.

If there is a technical matter that this operating manual does not address, or any other
question concerning this product, please contact Grant Instruments or your local
distributor, who will be able to provide any additional information.

3.0 Safety information

3.1 Safety compliance

The LTC2 meets the requirements of international safety standard IEC 61010: Safety
requirements for electrical equipment for measurement, control, and laboratory use.

3.2 Safety symbols

The symbols below are marked on the equipment and throughout this manual to indicate:

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3.3 Safety warnings

Read the whole of these instructions. Safety may be impaired if they are not
followed.

For the LTC2, only use liquids specified in these operating instructions, within
the specified temperature range. If the alarm lamp is illuminated the liquid
temperature may be above its recommended maximum. Do not inhale the
vapours given off as they may be toxic. Liquids should be safely discarded and
replaced.

Do not use the LTC2 with flammable heat transfer liquids.

Do not use the LTC2 to heat any sample material that could cause a fire or any
other kind of hazard.

Do not use the equipment in an area where there are aggressive or explosive
chemical mixtures.

If a potentially hazardous liquid is spilt onto or inside the equipment, disconnect
it from the power supply and have it checked by a competent person.

Before moving, disconnect from the mains power supply

It is the user’s responsibility to carry out appropriate decontamination if
hazardous material is spilt on the equipment.

If the alarm lamp is illuminated do not touch the liquid or the heater, they may
be very hot. Refill carefully, a hot heater can cause a spattering of very hot
water droplets and scalding steam.

Do not touch surfaces which become hot during high temperature operation.

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4.0 Operating instructions

The LTC2 weighs 25kg. Take necessary precautions when lifting.

To ensure protection the overtemperature cut-out must be set appropriately for
the heat transfer liquid selected (see table below).

If using non-recommended heat transfer liquids it is important to set the over­temperature cut-out to a value no higher than 25°C below the fire point of the
liquid.

Use fume extraction when using silicone fluids at elevated temperatures

Temp range

Recommended liquid

Comments

-30°C to 30°C

50% water, 50%
antifreeze (inhibited
ethylene glycol)

WARNING: Ethylene glycol is toxic – follow the
manufacturer’s instructions.
For safe disposal consult the local regulations.
Use a lid to reduce the dilution of the mixture
caused by condensing water vapour from the
air, and to maintain the cool down rate.

0°C to 30°C

80% water, 20%
antifreeze (inhibited
ethylene glycol)

5°C to 99.9°C

Water*

Water can be used but care should be taken
above 60°C as hot vapour can be dangerous.
Use a lid or polypropylene spheres above
60°C to ensure good performance & reduce
evaporation.
At temperatures approaching 99°C the
temperature performance will be affected due
to localised boiling.
The units should not be used to boil water.

70°C to 120°C

Silicone fluid
Viscosity ~20cs

Flash point ≥230°C
Fire Point ≥280°C

Dow Corning DC200/20 silicone fluid is a
suitable liquid – follow the manufacturer’s
instructions.
For safe disposal consult the local regulations.

4.1 Unpacking instructions

Standard equipment includes:

 LTC2 low temperature circulator
 Pump connector kit
 4 x Jubilee clips
 6m of insulated hose
 Mains cord

Remove packing materials carefully and retain them for future shipment or storage of the
equipment.

4.2 Recommended liquids

The following table lists the recommended liquids for different temperature ranges.
Always ensure the liquid used is safe and suitable for your working temperature. If using
non-recommended heat transfer liquids, it is the responsibility of the user to conduct an
assessment to ensure the intended fluid is compatible with the LTC2. If in doubt please
contact the Grant technical support team.

* See section 7.1 for further details

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4.3 Installation

Place the LTC2 on a level, non-combustible surface. Ensure that the mains
plug and the switch at the rear of the unit are easily accessible.

If the equipment has been transported or stored in cold or humid conditions,
condensation may form inside it. If that could have happened, allow time (at
least 2 hours at room temperature) for the condensation to evaporate before
using the equipment.

Do not block or restrict ventilation slots.

Do not connect to a power supply or switch on before filling the tank.

Drain before moving the bath. Before draining allow the liquid to cool below
50˚C.

Do not touch the condenser fins, they are sharp and may cause injury.

Connect the LTC2 to a grounded (earthed) electrical power supply with voltage
and frequency within the range specified on the serial number plate.

The LTC2 must only be connected to the mains using the mains cord supplied
or one with an identical rating (see section 9.4)

Ensure the mains switch and isolating device (power supply connector) are
easily accessible during use.

After transportation, let the unit stand in its intended working position for six hours. This
is to allow the oil to drain to the bottom of the compressor. This is normal procedure for
refrigeration compressors. Allow at least 100mm clearance from obstructions on all
sides so that there is free air flow through the unit, from the front to the back (this also
has the advantage that air is not blowing directly out of the sides onto instruments next to
the LTC2).

4.4 Electrical supply

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5.0 Operating procedures

Take care when lifting and removing the lid as it may be hot. Steam and hot
vapours can cause scalding.

Always use pump connectors and hoses that are suitable for the operating
temperature and liquid used. Check the pipe connections are secure.

Never disconnect any pipes or hoses while they contain very hot or very cold
liquids or while the LTC2 is pumping.

B

A

5.1 Operation

5.1.1 Liquid level

Fill the tank to an appropriate level with a liquid suitable for your working temperature;
see section 4.2 for liquid options. Allow for thermal expansion and contraction of the
liquid during operation and for any liquid in external circulation paths. If using liquids that
can evaporate then periodic checking and refilling should be completed. The low level
float switch will alarm if the liquid level drops below the minimum required level and the
unit will switch off the heater and stop temperature control.

5.1.2 Operation above 60°C

A lid or polypropylene spheres must be used above 60°C to maintain temperature control
and to ensure that the bath fluid temperature reaches the set point. They will save
energy by preventing excessive evaporation and reduce the frequency that the bath
needs to be refilled.

5.1.3 Using the pump

The LTC2 allows liquid to be pumped around a closed external system (not open to the
atmosphere). It cannot be used for circulation through an external open tank. The pump
is fitted with a blanking plate as standard. Fit a pump connector plate as shown below.
Ensure o-rings are located in the grooves, use silicone grease to hold the o-rings in
place. Note: the blanking/connector plates have a locating hole (see A below) to assist
correct alignment onto the pump moulding. It is important to verify the hole is aligned with
the corresponding locating pin (see B below) on the pump moulding. Failure to do so will
result in a leaking connection. Retain the blanking plate for refitting when the pump is no
longer required.

The LTC2 is supplied with insulated hose which is designed to operate at temperatures
between -40˚C to 80˚C. We recommend that suitable high temperature hose is used for

temperatures above 80˚C.

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Never use silicone oil with silicone tubing.
Allow the liquid temperature to fall below 50˚C before emptying.

Ensure all hoses are connected securely. Liquid will begin pumping
immediately once the LTC2 is switched on.

Pumping heat transfer liquid around an external system can lead to hazards that are
outside the control of Grant Instruments. It is essential that the user conducts a risk
assessment of the entire equipment installation to ensure that correctly rated materials
have been used throughout and that the system can be used safely.

5.1.4 Emptying the LTC2

The LTC2 tanks should be emptied to a safe level prior to moving. A drain tap is
included to allow convenient emptying. See section 5.2.3 for full details.

5.1.5 Setting up and switching on

Follow instructions in section 5.1.3 to attach the pump connector plate and insulated
hose. Before filling and switching on, attach the open end of the hose to the application,
taking care to note the inlet and outlet.

Add the appropriate working liquid to the bath to at least the minimum recommended fill
level such that the float level switch is fully raised.

The control unit can be powered either from the mains supply directly or via the cooler
unit (230V units only). An interconnect cable can be used to supply power from the
mains socket outlet on the rear of the cooler unit to the control unit (see Section 5.2.4).
Plug the mains cable into the fused power inlet socket on the rear of the refrigeration
unit.

Switch on the LTC2 control unit using the power switch on the rear. The motor will start
immediately and the buzzer will sound while the unit starts up. Switch on the
refrigeration unit using the power switch on the front of the unit. The LTC2 will start to
control at the set temperature.

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5.2 Using the LTC2

Float switch
Display

Alarm light

Control dial

Heater on light

Pump outlet plate

Over-temperature dial
Select button

Function button

5.2.1 Product description, control unit

5.2.2 Control unit product indicators

There are two indicator lights on the control unit:

 Heater on light (orange) marked
 Alarm light (red) marked

The alarm lamp will light to indicate the following faults:

 Float switch has operated due to low liquid level
 Over temperature cut out has operated
 Temperature probe fault

The cause of the alarm will also be shown on the display.

The display normally shows temperature in °C of the liquid being controlled.

The S(et) button is used to select and store values whilst the F(unction) button is used to
access menu options and cancel functions.

The main dial is used to change temperature values and other settable parameters.

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5.2.3 Product description, refrigeration unit front panel (grille removed)

Power switch

Over temperature protection reset

Freezing protection, 5˚C switch

Drain port

Drain insert

Condenser fins

The refrigation unit has a resetable over temperature protection which protects the unit
from overheating. This will be actuated when the working fluid temperature is between
110°C and 120°C. The unit can be reset by waiting for the liquid to cool below 100°C,
then unscrewing the black cap and pushing in the revealed button. Note, this protection
is in addition and separate from the over temperature protection on the control unit.

The freezing protection switch uses a low temperature thermostat to ensure the working
fluid never drops below 5°C. With the switch in the depressed/in position the cooling will
be switched off by a low temperature protecting thermostat. If water is used in the bath
this will prevent it from freezing. In the out/off position the thermostat is bypassed
allowing the unit to run at temperatures below 5°C.

The drain port and insert allow convenient emptying of the refrigeration bath. To drain
the unit first remove the drain insert from the holder and connect a suitable length of
hosing with a bore of 12.7mm (½’') to the drain insert. Have the non connected end of
tubing in a receptacle, suitable for the liquid to be drained. Push the drain insert into the
drain port and let the liquid drain. To release the drain insert push down the grey button
on the drain body and extract the drain insert. Liquid to be drained should not be below
10°C or above 50°C.

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5.2.4 Product description, refrigeration unit rear panel

Liquid

Set temperature range

H2O

0°C to 100°C

Oil

0°C to 120°C

LTL*

-20° to 50°C

Not used on this model

Power supply for

accessory pumps

Power supply for control unit

(220-240V units only)

Mains inlet and

220-240V unit

Not used on this model

Power supply for
accessory pumps

Mains cable inlet

110-120V unit

Mains fuses

5.2.5 Setting the control temperature

The temperature of the circulation liquid can be set using the S button.

1. Whilst the display is showing the bath temperature, press the S button. This will
cause the display to flash indicating that it can be set.

2. Use the main dial to set the desired temperature.

If no key is pressed for 10 seconds then the display will revert back to showing the
bath temperature and the set temperature will remain at its original value.

3. Press the S button to store the requested value and the display will revert to showing
the bath temperature.

If the temperature selected is higher than the current liquid temperature, the heater
light will come on.

5.2.6 Selecting liquid type

The liquid type determines the limits of the set temperature range.

1. Press the F button four times – the display will show the current liquid type.

2. Use the main dial to select the required liquid.

3. Press the S button to set the liquid type and return to normal temperature display.

Selection of the liquid types below changes the settable range as follows:

* LTL = low temperature liquid, for example 50% water/50% glycol

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5.2.7 Setting the over-temperature thermostat

An over-temperature cut-out dial with a temperature scale is located at the top right of the
unit. The over-temperature probe independently monitors the bath temperature and
switches the heater off if it goes above the cut-out threshold. For the LTC2, the
temperature cut-out threshold can be adjusted for convenience.

Coarse setting of the over-temperature thermostat

Rotate the temperature cut-out dial in line with the marked scale to the desired setting.
This should be higher than the set temperature to avoid operating the cut-out before the
set temperature has been reached.

If the alarm is triggered, it can be cancelled by pressing either the F or S button once.
The unit must then be switched off to clear the cut-out alarm. To continue to use the
LTC2, let the bath liquid cool by at least 5°C either naturally or by replacing the liquid
switch the unit off, wait 10 seconds and switch it on again to clear the alarm. To avoid
nuisance tripping the trip point needs to be set at least 5°C above the desired control
temperature.

Alternative setting of the over-temperature thermostat

Rotate the temperature cut-out dial to maximum (or at least a value above the level
required) and configure the set temperature to the cut-out level required. Leave the bath
to reach the set temperature and stabilise for at least 5 minutes. Turn the cut-out dial
slowly anticlockwise until the alarm lamp comes on and the alarm sounds intermittently.
The display will alternate between showing “Cut” and the liquid temperature. This gives
an over-temperature trip point at the set temperature. The audible alarm can be
cancelled by pressing either the F or S button once.

To continue to use the LTC2, let the liquid cool by at least 5°C, either naturally or by
replacing the liquid, switch the control unit off, wait 10 seconds or switch it on again to
clear the alarm. To avoid nuisance tripping the trip point needs to be set at least 5°C
above the desired control temperature.

5.2.8 Configuring a preset

The LTC2 can be configured with three temperature presets to allow the circulator to be
conveniently run at frequently used temperatures. Use the method below to configure
preset 1; other presets can be set in a similar manner.

Be aware that once a preset has been saved using the steps below, it will automatically
start once all the steps have been completed.

1. Press the F button and rotate the dial until the display shows “t-1”.

The display will alternate between the preset number and its temperature.

2. Press the S button to select the preset.

3. Use the dial to set the desired preset temperature.

If no key is pressed for 10 seconds then the display will revert back to showing the
bath temperature and the preset temperature will remain at its original value.

4. Press the S button to save the preset temperature.

The preset will automatically start as soon as the value is saved.

Preset temperatures and set temperatures are limited to between -20°C and 120°C. The
factory preset settings are shown in the following table.

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Preset

Set temperature range

t-1

37°C

t-2

56°C

t-3

72°C

5.2.9 Running a bath preset

1. Press the F button and rotate the dial until the display shows the correct preset.

2. Press the S button to select the preset.

3. Press the S button to set the bath to the preset temperature.

5.2.10 Completing a calibration

The LTC2 allows a two point calibration to be completed. The calibration menu can be
accessed by simultaneously pressing the F and S buttons for about 5 seconds.

The calibration temperatures are constrained by the temperature limits of the liquid type
setting. Calibration should be carried out using a traceable reference thermometer with
an accuracy of at least 0.1°C. This thermometer should be held securely in the centre of
the bath or vessel.

The calibration of the LTC2 is in two parts, a low temperature offset and a high
temperature offset. The high temperature calibration point must be at least 40°C higher
than the low temperature point.

Calibration points should be chosen to be at critical experimental temperatures where
accuracy is important or at the extremes of the working range of used temperatures.

If only the low temperature calibration point is set then the calibration will be performed
between this point and 100°C with the offset decreasingly linearly. If only the high
temperature calibration point is set then the calibration will be performed between 0°C
and this point with the offset decreasingly linearly.

If the thermometer value is entered before the unit is completely stable then the
calibration could be poor and liquid temperature readings will be incorrect. If the LTC2 is
not in accordance with the thermometer following calibration then it may not have been
successful and the unit should be reset.

Setting the low temperature offset

1. Adjust the set temperature to the required low temperature calibration point.

2. Allow the unit to stabilise for at least 5 minutes after a stable temperature condition
has been achieved.

3. Measure the liquid temperature by placing a reference thermometer into the centre of
the bath.

4. Press the F and S buttons simultaneously for approximately 5 seconds until “LCAL” is
shown.

5. Press the S button to select.

6. Use the main dial to update the display to show the temperature on the reference
thermometer.

7. Press the S button to store the temperature.

Press the F button to cancel the calibration.

8. Press the F button to return to the liquid temperature display.

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Setting the high temperature offset

1. Adjust the set temperature to the required high temperature calibration point.

2. Allow the unit to stabilise for at least 5 minutes after a stable temperature condition
has been achieved.

3. Measure the liquid temperature by placing a reference thermometer into the centre of
the bath.

4. Press the F and S buttons simultaneously for approximately 5 seconds until “LCAL” is
shown.

5. Rotate the dial until the display shows “HCAL” and press the S button to select.

6. Use the main dial to update the display to show the temperature on the reference
thermometer.

7. Press the S button to store the temperature.

Press the F button to cancel the calibration.

5.2.11 Restoring factory calibration settings

The restore factory calibration allows the unit settings to be reset if there is a problem
during calibration or you wish to cancel any of the calibration settings.

1. Press the F and S buttons simultaneously for approximately 5 seconds until “LCAL” is
shown.

2. Rotate the dial until the display shows “rST” and press the S button to select.

3. Press the S button four times (the display will show “Con.3”, “Con.2”, Con.1” and
sound the buzzer to confirm the factory reset has been completed.

5.2.12 Adjusting display brightness

The brightness of the display can be adjusted over a limited range (20% to 100%) if
required.

1. Press F and S buttons simultaneously for approximately 5 seconds until the display
shows “LCAL”.

2. Rotate the dial until the display shows “disP” and press the S button to select.

3. Rotate the dial between the settings and select required brightness

The displayed values show the display brightness

4. Press S button to save the value.

5. Press F button to return to the normal temperature display.

5.2.13 Setting a countdown timer

The LTC2 includes a countdown timer in minutes which triggers an audible alarm on
completion. The timer can be set between 1 minute and 6000 minutes (100 hours).

1. Press the F button twice – the display will show “Cloc”.

2. Press the S button to select.

3. Use the main dial to select “On” and press the S button to select. The display flashes
with time (in minutes) indicated. Rotate navigator control to set time required.

4. Press the S button to save and return to liquid temperature display with timer
countdown started.

When the countdown clock is set the display alternates between bath temperature and
time remaining in minutes.

When the countdown timer reaches zero the audible alarm will sound and the display will
alternate between the water temperature and “End”. The alarm can be accepted by
pressing the either the F or S buttons.

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Note: the LTC2 will continue to control at the set temperature after the timer
reaches zero – the heater will not switch off.

5.2.14 Cancelling the timer

The countdown timer can be easily cancelled.

1. Press the F button twice – the display will show “Cloc”.

2. Press the S button to select.

3. Use the main dial to select “Off” and press the S button to select. The display will
revert to the bath temperature and the timer will be cancelled.

5.2.15 Setting a high temperature warning alarm

The high temperature alarm sets a warning buzzer to sound if the bath temperature
exceeds a defined level.

1. Press the F button three times – the display will show ”Alar”.

2. Press the S button to select.

3. Use the main dial to select “On” and press the S button to select. The display flashes
the high temperature alarm value. Rotate the dial to set the high temperature alarm
required.

4. Press the S button to save and return to liquid temperature.

If the high temperature alarm value is exceeded then LTC2 will sound the buzzer
intermittently and show “-Al-” on the display. The alarm can be acknowledged by
pressing either the F or S buttons. However, the alarm is persistent and will trigger again
if the temperature still exceeds the high temperature value. The alarm can be cancelled
by following the steps above but using the dial to select “Off” in step 3 and pressing the S
button to confirm.

Note: the high temperature alarm will not switch off the heater.

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6.0 Technical specifications

Ambient temperature range

5 to 40°C

Altitude above sea level

Up to 2,000m (6,500ft)

Operating environment

Indoor use only

Maximum relative humidity

80% RH up to 31°C decreasing to 50% RH at 40°C

Specification

LTC2

LTC2L

Typical cooling power at an
ambient of 20°C

@ 20°C

250W

@ 0°C

140W

@ -10°C

100W

@ -20°C

35W

Stability (DIN 12876)

±0.1°C †

Uniformity (DIN 12876)

±0.1°C

Settable temperature range

-20°C to 120°C

Working temperature range

-20°C to 100°C

Refrigerant R134a

140gm

Tank capacity

5L

Top opening

110/145mm

Max pump head pressure

210mBar

Max pump flow rate

16L/min

Safety 100°C limit

Cut-out

Safety H2O freezing protection

5°C thermostat & switch

Max current consumption (both units)

8.0A

15.5A*

Heater power

1.3kW

1.4kW

6.1 Operating conditions

6.2 Electrical details

Mains supply: 220-240V @ 50Hz or 110-120V @ 60Hz
Pollution degree: 2
Installation category: II

Mains supply voltage fluctuations are not to exceed ±10% of the nominal supply voltage.

6.3 Performance

*Requires two separate mains cords

† Temperature stability may be affected (±0.3C) in the presence of strong RF fields (10V/m) at
380-400MHz. This level of interference is very unlikely and is only likely to be encountered in
electrically noisy industrial locations as defined in EN61326)

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7.0 Technical Tips

7.1 Which water should you use in your bath?

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 de­oxygenated, 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
to 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 ion­exchange system that incorporates a salt back-flush system to regenerate the ion­exchange resin as this can leave sodium ions that are very corrosive to stainless steel.

7.2 How to prevent rust in water baths

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 usually be removed by using a household cleaner such as Duraglit or Silvo
metal polish.

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7.3 How to prevent algae and bacteria?

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 can 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.

8.0 Warranty information

When used in laboratory conditions according to this manual, this product is guaranteed
for FOUR YEARS against faulty materials or workmanship.

Extended warranty for years four and five can be purchased by contacting our sales
department at [e-mail].

9.0 Maintenance and service

9.1 Routine maintenance

The over-temperature cut-out on the control unit should be checked periodically by
turning the over-temperature dial with a screwdriver anticlockwise until the alarm lamp
comes on. The control unit will also sound a buzzer and “Cut” will be shown on the
display. The over-temperature dial should then be turned to the maximum setting without
the alarm cancelling. The control unit should be powered off and back on to confirm that
the cut-out can be reset correctly. If the alarm lamp fails to light when the value indicated
on the over-temperature dial is more than 10°C below the current temperature as
indicated by the main display, then the unit should be checked by a competent person.

The float liquid level protection should also be checked periodically by lowering the level
of liquid in the bath and noting that the unit cuts out with the top turn of the heater still
immersed in the liquid.

When hoses are fitted to the pump they should be inspected periodically and replaced as
necessary to avoid hose failure.

No other routine maintenance is required.

9.2 Cleaning

Regular maintenance of the LTC2 is important to allow the unit to perform to its
specification and is required for warranty validity.

The removable grille enables easy access to the condenser for cleaning. Cooling power
will be reduced if the fins become clogged with dust. The condenser fins (see section

5.2.3) should be examined monthly and, if necessary, use a vacuum cleaner nozzle and

soft brush to remove the dust.

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De-scaling products may be toxic and manufacturer’s instructions should
always be followed

R unit

Fuse rating

R2

15AT

R2L

5AT

Clean the outside of the equipment with a damp cloth, using water only. Do not use
chemical cleaning agents. Before using any other cleaning or decontamination method,
check with Grant Instruments or your local representative to make sure that the proposed
method will not damage the equipment. Scale on immersed parts can be removed using
chemical de-scaling products designed for use on equipment that has metal parts.

9.3 Fuses

The control unit fuses are internal and should not need to be replaced. Please contact
the Grant Instruments service department if the unit has a fuse fault.

The refrigeration unit has externally accessible fuses that can be changed by a qualified
technician. Disconnect the unit from the power supply socket. For the 220-240V unit
only, remove the IEC power plug from the rear of the unit. Press down the fuse drawer
catch and pull out. Check fuses and if necessary replace. Push the fuse drawer back in
until fully engaged and replace the IEC plug.

For the 110-120V unit, twist the fuse holder cap anticlockwise to release the fuse. Check
fuse and if necessary replace. Refit the fuse in the unit and twist clockwise to secure.
Repeat for the second fuse.

Replacement fuses must be 1.25” x 0.25” anti surge ceramic type with the rating defined
in the following table:

9.4 Replacing the mains cord

Any replacement mains cords used for the control unit or refrigeration unit must meet the
same specification as the one originally supplied to maintain the safety of the unit.

All mains cables (including the interconnect mains cable) must have the following
markings; <HAR>, HO5VV-F 3Gx1mm2 90°C and be rated to carry 10A. The mains plug
and IEC connector must carry approvals from a European certification body (e.g. BSI,
VDE or equivalent).

The LTC2L (110-120V) control unit and refrigeration unit both have fixed mains cords
which should not be replaced.

9.5 Routine safety tests

If routine tests are to be made, we recommend a test of the integrity of the protective
earth conductor and an insulation test at 500V DC. Routine flash tests are not
recommended for any electrical equipment, because repeated high voltage tests degrade
insulation materials.

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Operating Manual Page 20

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Pump Product

Description

VTP1

Max head pressure: 1000mBar
Max flow rate: 9 L/min

VTP2

Max head pressure: 1700mBar
Max flow rate 12 L/min

17927

Pump lid for LTC2

9.6 Service

If service is required, switch off the unit and contact Grant Instruments or your local
representative for repairs.

Please note, all returned units must be accompanied by a Return Materials Authorisation
(RMA) number, obtainable by contacting the Grant service department (details below).

Service Department
Grant Instruments (Cambridge) Ltd
Shepreth
Cambridgeshire
SG8 6GB
UK

Tel: [phone]
Fax: [phone]
E-mail: [e-mail]

10.0 Optional accessories

10.1 Alternative pump

A pump comes as standard on the LTC2. If greater head (pressure) is required you can
choose from two accessory pumps and the appropriate pump lid. Add L to pump part
numbers for 120V (60Hz) versions. See the Grant website at www.grantinstruments.com
for full technical specifications.

A full listing of product accessories and options is available in the Grant Scientific
Reference Catalogue (a copy of which is available upon request) and on the Grant
website at www.grantinstruments.com.

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11.0 Troubleshooting

Symptom

Possible cause

Action required

Display shows
“Cut”

Over-temperature
cut-out has operated

Check the set temperature is correct and that
the over-temperature cut-out temperature is
set at least 5°C above the set temperature.
Refer to section 5.2.7 for setting instructions.

If the over-temperature cut-out temperature is

correctly set but the unit still shows a “Cut”

alarm then the unit has an internal fault and
must be repaired before it is used again.

Temperature
does not rise
when expected

Set temp is lower
than liquid temp

Set temperature is
too close to ambient

Check that the bath set temperature is correct
(see section 5.2.5).

Increase the set temperature (see section

5.2.5)

Temp continues
to rise when not
expected

Set temp is higher
than liquid temp

Check that the bath set temperature is correct
(see section 5.2.5).

Unit fails to cool

Compressor
overheated causing
internal over­temperature
thermostat to operate

Wait for compressor to cool, when thermostat
will reset and compressor will switch on
again.

Alarm light on

Over-temperature
cut-out has operated

Low liquid level float
switch has operated

Check the over-temperature cut-out is set
appropriately (see section 5.2.7).

Check that the liquid level in the bath is
adequate.

Set temperature
too restricted

Liquid type set does
not allow required set
point

Change to different liquid type (see section

5.3.5).

Display shows
“Flot”

Liquid level has
dropped below
minimum level

Check that the liquid level in the bath is
adequate.

Display shows
“–Al-”

High temperature
warning alarm has
tripped

Check that the bath set temperature is correct
(see section 5.2.3).

Check that high temperature alarm is correct
(section 5.3.4).

Check that the liquid level in the bath is
adequate (see section 6.3 for minimum fill
levels).

Display shows
“Er H”

Incorrect calibration
value

The high temperature calibration point is less
than 40°C above the low calibration point –
choose a higher temperature (see section

5.2.10).

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Operating Manual Page 22

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Display shows
“Er L”

Incorrect calibration
value

The low temperature calibration point is less
than 40°C below the high calibration point –
choose a lower temperature (see section

5.2.10).

Display shows
“Er d”

Incorrect calibration
value

The calibration value is greater than 10°C
from the set point – check thermometer
reading and set point (see section 5.2.10).

Display shows
“Open”

Faulty temperature
probe

Have a competent person check the probe for
an open circuit fault or contact Grant.

Display shows
“Shrt”

Faulty temperature
probe

Have a competent person check the probe for
a short circuit fault or contact Grant.

Unit showing
erratic
temperatures

Calibration values not
set correctly

Restore the factory calibration settings (see
section 5.2.11) then re-calibrate if required
(see section 5.2.10).

Display shows
“Hot”

Heating water at or
near to boiling without
lid

Heating very large
volumes of liquid with
large thermal losses

Add a lid to reduce thermal losses and leave

unit running with the “Hot” warning present. If

the alarm has not cleared within 1 hour
contact Grant.

Add measures to reduce thermal losses and

leave unit running with the “Hot” warning

present. If the alarm has not cleared within 1
hour contact Grant.

Display shows
“Fuse”

Faulty fuse(s)

Have a competent person check the internal
fuses or contact Grant.

Display shows
“Crct”

PCB fault

Have a competent person check the product
or contact Grant.

Display shows
“Self”

Safety relay fault

Have a competent person check the product
or contact Grant.

Stirrer motor not
rotating

Stirring propeller or
pump impeller is
obstructed

Faulty motor

Clear obstruction.

Have a competent person check the motor or
contact Grant.

Display shows
“Cold”

Accidentally entered
manufacturer reset
mode

Warning can be cleared by pressing S button,
but note that all settings (including any factory
calibration) will be reset to the default values.
Contact Grant Instruments service
department for assistance if required.

For any other errors or service requests, please contact Grant Instruments service
department.

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12.0 Contact Grant Instruments

At Grant we are continuously trying to improve the performance we offer our customers.
If you have any feedback on Grant’s products or services we would like to hear from you.
Please send all feedback to:

Quality Manager
Grant Instruments (Cambridge) Ltd
Shepreth
Cambridgeshire
SG8 6GB
UK

Tel: [phone]
Fax: [phone]
E-mail: [e-mail]

13.0 Compliance

WEEE directive

Grant Instruments complies fully with the Waste Electrical & Electronic Equipment
(WEEE) regulations 2006. We are a member of the B2B compliance scheme (Scheme
Approval Number WEE/MP3338PT/SCH), which handle our WEEE obligations on our
behalf. Grant Instruments have been issued with a unique registration number by the
Environmental Agency, this reference number is WEE/GA0048TZ.

For information regarding WEEE collections in the UK please contact our B2B
Compliance Scheme directly on 01691 676 124.
For other countries please contact your equipment supplier.

For General WEEE information please visit: www.b2bcompliance.org.uk

RoHS directive

All the products covered by this manual comply with the requirements of the RoHS
Directive (Directive 2002/95/EC).

Electrical safety and electromagnetic compatibility

All the products covered by this manual comply with the requirements of the Low Voltage
Directive (2006/95/EC) for electrical safety and the EMC directive (2004/108/EC) for
electromagnetic compatibility. See the Declaration of Conformity on the inside back
page.

LTC2 30933 V2
Operating Manual Page 24

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Notes

30933 V2 LTC2
Page 25 Operating Manual

www.grantinstruments.com

Grant Instruments
(Cambridge) Ltd

Shepreth
Cambridgeshire
SG8 6GB
UK

Tel: [phone]
Fax: [phone]
Email: [e-mail]
www.grantinstruments.com

Printed in England – LTC2 /30933 /V2 /DMN C72 /Nov 2012