Customer Service

After-sales support and customer service is an integral part of LTH’s intelligent measurement solution. It is LTH’s intention to develop a close and continuing relationship with its customers throughout the entire product lifecycle

Our service commitment

From the initial purchase, through planned maintenance, emergency support, installation, on-site commissioning, product training, trouble-shooting or calibration to traceable standards LTH can provide all the support and service you could require.

Planned preventative maintenance carried out at predetermined intervals scheduled to suit customer’s requirements can minimize the risks of unplanned breakdowns, extend product life cycles and help to optimize production processes.

Specialist skilled technicians from our service division ensure that your process control equipment is functioning and operating as it was originally designed, with fully traceable calibration certificates and service documentation provided electronically to customers.

LTH are an ISO9001: 2015 registered company who offer a 3 year warranty on all their instruments. In the event that your instrumentation fails or needs to be returned to our repair facility, it will be dealt with quickly and efficiently ensuring as little disruption as possible.

Through our on-site and in-house calibration facilities we are able to ensure that your instrumentation remains within specification year on year.

Whether you are returning items for calibration, modification, repair or credit please complete the goods return form before returning the items to our service department.

Our LTH trained world-wide distribution and local representative network ensures customers have prompt access to LTH’s in-depth product knowledge, measurement know-how, country specific technical expertise and application advice.

Ask the experts

Do you have a liquid measurement application you would like to talk to us about?

Contact an Expert

After-sales support and customer service forms

Between the sales and Customer Care team there is always someone on hand who will be there to assist in any matters that may arise. However, we have a few online forms that we hope will help speed things up


  • What is the warranty period for LTH products?
    Products manufactured by LTH Electronics Ltd are guaranteed against faulty workmanship and materials for a period of three years from the date of despatch, except for finished goods not of LTH manufacture, which are subject to a separate agreement. All sensors made by LTH Electronics Ltd are thoroughly tested to their published specification before despatch. As LTH have no control over the conditions in which their sensors are used, no further guarantee is given, although any complaints concerning their operation will be carefully investigated.
  • How do I know if my LTH product is still covered by a warranty?
    Please contact our sales department with the serial number of your product. Our sales department will be able to check our records and confirm if the warranty has expired or not.
  • Can you service my LTH instrument?
    Yes we can, we offer an onsite service for planned maintenance, emergency support, installation, on-site commissioning, product training, trouble-shooting or calibration to traceable standards. Alternatively the product can be returned to our service department at our factory in Luton.
  • I am not based in the UK; can you service my LTH product?
    Please contact your local LTH global partner to see if this is possible. Their details can be found on the Global partner’s page on our website. If there is not a global partner listed for your country, please contact our sales department to see how we can help you.
  • How quickly can you service my product?
    For UK customers we can normally get to site within 48 hours of the request. For non-UK customers please contact your LTH global partner or our sales department to see what we can do.
  • I have one of your competitor’s instruments – can you service this?
    We can calibrate and service many of our competitor’s products, please contact our sales department with the product details to see if this is possible for your product.
  • I wish to purchase an LTH product but can I install this myself?
    Yes, all our instruments are supplied with a printed quick start guide with a PDF version of the user manual available to download from our website. We offer an optional pre-configuration service to set your instrument to the parameters required before it is delivered to you simplifying installation and set-up.
  • I am a contractor who looks after a number of sites which have LTH products installed. How do I calibrate and service them?
    We offer training courses for our products. Please contact our sales department for details and costs.
  • In Conductivity measurement what is the relationship between µS/cm (microsiemens/cm) & mS/cm (millisiemens/cm)?
    1ms/cm (millisiemen/cm) is equal to 1000µS/cm (microsiemens/cm)
  • What is the difference between micromhos/cm and microsiemens/cm?
    There is no difference. Micromhos is more common in the U.S, while microsiemens is more commonly used in Europe.
  • What is the relationship between Resistivity and Conductivity?
    Resistivity is simply the reciprocal of conductivity. Generally Resistivity measurements are used in low conductivity or pure water applications.
  • How does temperature affect conductivity measurement?
    You will notice that whenever the conductivity of a solution is quoted it is usually referred to a temperature. This is because the conductivity of a solution varies not just with the amount of dissolved salts, but also with temperature. If the conductivity measurement is going to be used to determine for instance the concentration of sulphuric acid it is essential that the temperature effect is eliminated. This is achieved by measuring the solution temperature and compensating the conductivity measurement to the reading that would be given at a standard temperature. This is usually 25°C. Different solutions will have different coefficients in the order of 1-3 %/°C. The temperature compensation will be quoted in %/°C and to a base temperature. When comparing different conductivity readings on different instruments it is essential that the temperature compensation is performed in the same way. A typical compensation rate of 2%/°C is generally used, but where more accuracy is needed a variable coefficient is essential. It should also be noted that the conductivity of pure water below 0.1 uS/cm (10M°.cm) has a very large and non-linear temperature dependence. In order to obtain accurate readings in this range of measurement it is essential that the instrument has the correct temperature facilities.
  • How do I clean my Contacting conductivity cell?
    The following maintenance information applies to the conventional electrode type of conductivity cell. The area of the cell that is sensitive to fouling are the electrode surfaces, these must fully “wet” to ensure accurate measurements are made. Moulded cells are often used in applications where a high level of contamination may be expected. This can include contaminates which do not contribute directly to the measured conductivity, e.g. organics, rust and suspended solids, but may form deposits on the electrode surface. In general these may be cleaned with the bristle brush provided and a weak detergent solution mixed with scouring powder. Problems may occur in hard water areas where the gradual formation of scale will reduce the active area of the electrodes. Simple brush cleaning alone will not remove a hard deposit from the electrode surface. If scaling is suspected the cell should be removed from the system and treated with a 10% solution of hydrochloric or formic acid. The presence of bubbles will indicate that the scale is being dissolved. Cleaning is completed when the bubbles cease and usually takes 2-3 minutes. The cell must be thoroughly rinsed to remove all traces of acid before it is replaced in the system. Note: Follow the supplier’s data sheet when handling acids and dispose of carefully according to your local authority regulations. Cells with stainless steel electrodes are generally used in applications where a low conductivity is combined with a low level of organic contamination and cleaning is rarely necessary. Errors in measurements can often be traced to faulty connections or incorrect setting on the instrument. However if contamination is suspected the cell should be removed from the system and cleaned if necessary. Handling of the cell electrodes will leave residues of oils and greases which will affect the wetting of the surfaces, leading to inaccurate readings. After touching the electrodes wash with a detergent solution and rinse thoroughly. After rinsing check that the surfaces maintain a complete film of water for approximately 10 seconds.
  • How do I calibrate my Electrodeless conductivity sensor?
    The LTH Electrodeless conductivity instrument and sensor can be calibrated using the appropriate loop resistor(s). Please refer to the appropriate instrument manual or contact our sales department for further details.
  • How do I clean my Electrodeless Conductivity sensor?
    LTH Electrodeless conductivity sensors do not require cleaning unless the centre hole through the sensor becomes blocked.
  • My ECS42T Electrodeless conductivity sensor that has just been delivered has a black rubber boot fitted to it. What is this for?
    This is a protective cover to prevent the sensor being damaged during transit. This must be removed before the sensor is used.
  • I am installing a pH electrode in a tank which is emptied each day. Will this affect the pH electrode?
    Yes, the life of the pH electrode will greatly shortened. All pH electrode bulbs should be kept wet at all times.
  • How should I store my pH electrode?
    Never store a pH electrode dry. We would recommend a Potassium Chloride or KCl solution. We recommend any concentration between 2.0 M and 3.8 M. An alternative choice is a pH buffer solution. A pH 4 buffer solution is best since it will keep longer, but pH 7 is also acceptable. Never store the pH electrode in deionised water (DI).
  • Is automatic temperature compensation for pH measurement necessary?
    To obtain the most accurate pH measurement, it is important to compensate for temperature. Temperature has two significant effects on pH readings. The solution pH and the electrode output will both change at different temperatures. These two effects, either together or separately, can lead to errors in calibration, measurement and control.
  • How should I install a pH Sensor?
    A pH sensor must be mounted at least 15° above the horizontal to consistently function properly. The liquid in the sensor contains small air bubbles. If not inclined slightly above horizontal, a bubble can adhere to the pH bulb where it will affect the sensor’s performance.
  • How often should I re-calibrate or buffer my pH electrode?
    This varies depending on a number of factors: Accuracy required, how clean the application is, process operating temperature and pressure. We would normally recommend that you initially calibrate once per week. If you find after a number of weeks the calibration is remaining within tolerance you can then extend the period between calibrations.
  • How do I clean my pH electrode?
    1. General: Wash with a solution of liquid detergent and warm water by gently scrubbing with a soft tooth brush or soft tissue. Follow with a thorough rinse in D.I. or tap water. 2. Inorganic Deposits: Try to dissolve the deposit by immersing the electrode bulb in 0.1N Hydrochloric acid for a few minutes followed by a thorough rinse with D.I. or clean tap water. Then proceed with the general cleaning in Step 1 of this section. 3. Organic Oil, Grease Films or Fingerprints: Wash the electrode bulb with the solution in Step 1 of this section. Wash the tip with acetone. Follow with the general cleaning procedure in Step 1 of this section. Note: Depending on the extent of the oil and/or grease contamination, the electrode may be damaged beyond recovery. 4. Plugged or Dry Ceramic Liquid Junction: Try at least one of the previous 3 steps in this section. Place the electrode in KCI solution, 2M or stronger. Heat slowly to 50ºC then let cool to room temperature. Repeat as necessary.
  • I have heard that Low Conductivity pH measurement can be difficult?
    Yes, once the conductivity drops below 50µS/cm problems can be introduced. Standard pH electrodes contain 3.5M KCl as a reference gel. Samples like DI water and other low ionic solution contain very small amounts of salt. These solutions try to leach ions from the reference gel to raise their conductivity levels. This results in very slow, sluggish, and unstable readings from a conventional pH electrode. Once you go below this value we recommend using an electrode suitable for Low Ionic strength water and Low Ionic strength buffer solutions.
  • What is the output of pH electrodes?
    Our pH electrodes conform to the Nernst Equation for pH output as a function of temperature. At 25°C, the pH output is 59.16 millivolts per pH unit. The electrode will give a zero output at a pH of 7.0 at all temperatures.
  • What is the range of measurement for Redox or ORP?
    Redox or ORP is expressed in millivolts (mV). A range of -1999 mV to +1999mV is common with ORP instruments.
  • What does Redox / ORP measure?
    Redox or ORP measures the total activity of a solution in mV or the total of reducing and oxidizing activities in a solution. Redox or ORP measurement ORP is useful for monitoring and controlling the addition of oxidizing agents such as chlorine, bromine, and ozone or reducing agents including cyanide, sodium bisulfite and metabisulfite.
  • How do I calibrate my Redox electrode?
    A Redox electrode does not have to be “calibrated” but it can be tested if required by using a Standard Redox or ORP Test Solution. LTH can offer a suitable Redox test solution. Please contact our sales department with your request.
  • How should I install a Dissolved Oxygen Sensor?
    A Dissolved Oxygen sensor must be at least 15° above horizontal to consistently function properly. The liquid in the sensor contains small air bubbles. If not inclined slightly above horizontal, a bubble can adhere to the cathode where it will affect the sensor’s performance.
  • What is the difference between a galvanic and polargraphic Dissolved Oxygen electrode?
    The Galvanic cell consists of two electrodes and an electrolyte. A galvanic electrode produces its own current. A silver or gold cathode and a lead anode are immersed in an Alkali electrolyte with a gas permeable membrane separating the sensor from a test solution. Polargraphic electrodes have a silver anode and a Platinum or gold cathode. A voltage is applied to the electrode to bring about a polargraphic reduction of the diffused Oxygen. A “Polarizing” voltage is provided by the Dissolved Oxygen instrument.
  • Does Temperature affect my Dissolved Oxygen readings?
    The membrane permeability is temperature dependent, so to obtain accurate measurements of oxygen solubility temperature compensation is applied by the instrument. The effect is large, in the order of 6-7% per °C, so considerations must be made to allow stabilisation of the sensor when calibrating or taking measurements if temperature changes are taking place.
  • How does atmospheric pressure affect my Dissolved Oxygen readings?
    Oxygen saturation of water is different at different pressures. Correction charts are provided in most instruction manuals. Many instruments automatically compensate for barometric pressure. The barometric pressure is either measured by the instrument or manually entered by the user.
  • How do I calibrate my Dissolved Oxygen sensor?
    Zero calibrate the probe by immersing it in a saturated solution of sodium sulphite. For full-scale calibration the sensor can be calibrated in free air.
  • In Level measurement what terms are used to describe the level control functions?
    POINT LEVEL: Product level distance measured from the tank or vessel’s bottom. HIGH LEVEL: Maximum level at which “vessel full” indication is required. LOW LEVEL: Minimum level at which “vessel empty” indication is required. HIGH HIGH LEVEL: Above maximum expected level, can be an additional high alarm set point to initiate emptying of a tank. LOW LOW LEVEL: Below minimum expected level, can be an additional low alarm set point to initiate filling of a tank. PUMP CONTROL LOGIC: When applied to overhead tank level control, the pump is STOPPED if the level is equal to or greater than the maximum desired level and does not RESTART until the level is equal to or less than the minimum desired level. Thus the level is maintained between the minimum and maximum point levels. If applied to sump level control, the pump is STOPPED when the level is equal to or less than the minimum desired level and RESTARTED when it is equal to or greater than the maximum desired level. Thus the level is maintained between the minimum and maximum desired levels.
  • I notice some of the Level and Flow transmitters look very similar.
    Yes, Ultrasonic level transmitters can also be used for Open channel flow measurement. Ultrasonic measurement provides a non-contacting technology for distance measurement which can be configured to provide accurate continuous measurement of product depth / height. Ultrasonic measurement provides maintenance free height or depth measurement of solids, chemicals and water, from food ingredients to corrosive chemicals, waste water and sewage. As this technique makes no contact with the material, there is no on-going cleaning, wear or maintenance schedule.
  • What applications should I avoid with ultrasonic level sensors?
    The application to avoid with ultrasonic level are extreme foam, vapour or turbulence. Foam, vapour and turbulence can absorb and /or deflect away a substantial portion of the return signal.
  • Why should I use a Radar level transmitter?
    Radar operates without influence on the signal by either vapour, temperature or pressure. There is also no effect on the measurement by material changes such as density, dielectric properties, and viscosity. Radar level transmitters are non-contacting, reducing maintenance and service to a minimum. Radar is one of the most widely effective level measurement techniques available.
  • What is the principle of operation for an Electro-magnetic flowmeter?
    The working of these meters is based on Faraday’s Second Law of Electromagnetic Induction. It states that, a conductor moving in a magnetic field with the direction of its motion perpendicular to the magnetic field generates an EMF across it and the direction of the EMF is perpendicular to both, the magnetic field and the direction of motion. The generated EMF is proportional to the magnetic flux density, B, the velocity of conductor v and the length of the conductor l. In the flow meter the magnetic field is generated by exciting the coils and the conductor is the liquid itself, under measurement with the length equal to the diameter of pipe.
  • For Electro-magnetic flowmeters what does the minimum conductivity of the liquid have to be?
    The electrical conductivity of the liquid to be measured should have a minimum conductivity of 5 µS cm (microsiemens/cm)
  • With Electro-Magnetic flowmeters what can cause incorrect flow readings?
    The pipe not completely full during operation, Entrained air in the liquid, Pulsating flows, Grounding issues which can include: PVC or internally lined pipe with no grounding rings used, Faulty ground connection
  • What are grounding rings?
    Grounding rings are stainless steel rings with an internal diameter matching the magflow meter ID. If required a pair of grounding rings are required, one on the inlet side and one on the outlet side of the meter body between the flange mountings. Gaskets are required on both sides of each grounding ring.
  • When are grounding rings needed?
    Grounding rings are required when the piping material is not electrically conductive, such as PVC or cement lined ductile iron pipes. A wire connection must be made to both grounding rings and to the meter body flanges.
  • Are gaskets needed in the installation of Magflow meters?
    Yes, it is always recommended to use gaskets to ensure a good seal to the flange connections. If grounding rings are used then gaskets are a must.
  • Can Electro-magnetic flowmeters be used in the food & beverage industries?
    Yes, it is possible to use the Smag flowmeter which has a Stainless Steel 304 body and either a DIN or clamp process connection.
  • How do the SGM-100 Clamp on flow meters work?
    The SGM-100 utilizes two transducers which work as ultrasonic transmitters and receivers. They are clamped on the outside of a closed pipe at a specific distance from each other. They can be mounted in a V position (the sound crosses the pipe twice), in a W position (the sound crosses the pipe 4 times) or in a Z position (mounted on opposite sides of the pipe – the sound crosses the pipe once). The selection of the mounting position depends on the pipe and liquid characteristics. The SGM-100 operates by alternately transmitting and receiving a frequency modulated burst of sound energy between the two transducers and measuring the transit time that takes the sound to travel between them. The difference in measured transit time is directly and exactly related to the velocity of the liquid inside the pipe.
  • Can the SGM-100 clamp on flowmeters be used on non-conductive liquids?
    Yes, ultrasonic clamp-on flowmeters can be used to measure the flow of a wide range of electrically conductive and non-conductive liquids.
  • Does the pipe material affect the operation of the SGM-100 flowmeters?
    It is possible to select the pipe material and lining type in the instrument menu.
  • Do the Quadbeam range of Suspended solids sensors drift due to contamination or change in light source?
    No, the four beam alternating light sensors self-compensate for component ageing, sensor fouling and daylight interference
  • Will the Suspended Solids sensors leak?
    We transmit light directly through the polymer sensor housing so there are no lenses to allow liquids to leak in.
  • Can the Suspended solids sensors be used in sanitary applications?
    Yes we have 3A certified sensors. Our range of sensors covers both immersion and sanitary applications.
  • Are the Suspended Solids sensors OK with Cleaning in place (CIP)?
    Yes, the sensors have been designed to withstand the rapid temperature cycling which occurs during CIP cleaning cycles.
  • Will entrained air have an impact on the Suspended solids reading?
    Yes, the installation and positioning of the sensor is important; for best results refer to the Suspended solids sensor installation guide.
  • When measuring Suspended solids / Turbidity is it important to calibrate against the measured product and conditions?
    To best control or monitor your application it is best to set up and calibrate against samples of the measured product.
  • The Klay Instruments range of transmitters are manufactured in Stainless steel enclosures – why?
    This makes the products rugged, durable and easy to clean as well as suitable for use in the food, beverage and pharma industries.
  • Are the Klay level and pressure transmitters affected by cleaning in place (CIP) and steam in place (SIP) processes?
    No – they have active temperature compensation.
  • I have another manufacturer’s pressure transmitter installed in a pipe which I need to change but the process connection looks special?
    We have more than 50 type of process connection available; please contact our sales department with your request.
  • What are the advantages of a Flush Mounted Diaphragm on the Klay transmitters?
    Strong and small diaphragm, Laser welded, Standard polished, minimum oil filling between sensor and diaphragm by using the Flush Diaphragm Technology. Wave structure (back-up) behind diaphragm, Equal to diaphragm structure.Good protection against overpressure with Perfect long term stability. The Pressure sensor is very close to the process
  • Why don’t the Klay transmitters use oil filled capillary system?
    There is minimum oil filling between the sensor and diaphragm by using the Flush Diaphragm Technology. This reduces sensitivity from temperature fluctuations. Produces a reduction in spares / accessory costs by using less oil. Uses a Smaller diaphragm which is less sensitive for damaging.
  • Why should you apply Stainless Steel diaphragms instead of Ceramic diaphragms?
    Ceramic diaphragms are not polished and have a raw / rough finish and can be attacked by Nitric Acid. With ceramic diaphragms there is no protection against pressure spikes. The O-ring’s have the following problems: They deteriorate with age and must be periodically replaced, they are not gas tight and cannot withstand all process media.

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