ELSEC 764 - Environmental monitor & datalogger

See also ELSEC 774 Universal Light Monitor (Lux, UV, IR, Temp)

Replaces 4 separate instruments:

Ultra Violet (UV) level
Visible Light (Lux or Foot-candles)
% Relative Humidity
Dew point
Temperature (°C or °F)
Sized like a small mobile phone
Easy one handed operation
Large, easy to read display
Maximum & minimum with time
Optional data logging

This single instrument enables measurement of the four parameters that cause most damage to buildings, valuable objects, documents etc: ultraviolet and visible radiation, humidity and temperature.

For many years it has been recognised that one of the major causes of damage to museum objects and other antiquities is the fading and rotting effect of light on the object. The most damaging part of the illumination is its ultraviolet (UV) content. Since 1976 Littlemore Scientific (ELSEC) has been providing instruments that enable the conservator to measure the UV content of light and thereby protect valuable exhibits. Using the 764, measurements can be taken of the proportion of UV present (mW/lumen), the total amount of UV (mW/m²), the amount of visible light present as Lux or Foot-candles. Temperature can be measured in °C or °F, humidity is shown as % Relative Humidity (% RH) and dew point. The displayed units can easily be changed by the user.

Provision is made for user calibration of the RH sensor using saturated salt solutions. A calibration kit is available as an optional extra.
Our comment: The RH-sensor needs rather frequent re-calibration, since it shows a considerable drift even within month. Fortunately, calibration of the ELSEC 764 is very easy. Response time of the RH sensor is relatively slow, therefore it is not ideal for quick measurements. If you are looking for a reference instrument to calibrate your thermohygrographs you better choose a different instrument.

Maximum and minimum values and their time of measurement are displayed for each parameter.

Much trouble has been taken to make the 764 as easy to use as possible. Anyone can take measurements straight out of the box with little, if any, reference to the instruction manual. The appropriate button is pushed depending on the measurement required and the reading is taken. The unit automatically turns off 10 seconds after the last reading unless a button is held down for over 5 seconds, this causes continuous measurements to be taken until another button is pressed. The large 8 line display enables an easy to use menu system to select the more advanced functions, change units etc.

Data logging (version 764C only)

The optional data-logging function enables over 10,000 readings of all four parameters to be automatically taken at selectable intervals (every 10 seconds to 1 hour). The saved data can then be transferred to a computer by a wireless infra-red link (IrDA compatible). Many modern computers have an infra-red interface built in; for those that do not, adapters are available. When logging data the 764 can be turned off to save power and the built in clock will turn the unit on whenever a reading needs to be taken, this enables a 764 to be left taking readings for months at a time. Software is provided to save the logged data in a CSV format that can be accessed and displayed by many programs (e.g. Microsoft Excel). A seperate program allows the graphical display of the data.

Units of measurement for UV

Traditionally UV has been measured in museums as the proportion of ultraviolet present. This result is useful for checking a particular lamp or window because the proportion of UV does not change with the distance from the light source. Using a simple rule, the amount of UV on an object can be limited (it is usual to arrange that the proportion of UV should not exceed 75 mW/lumen in museums). The actual amount of damage done is determined by the total amount of UV falling on the object, so it is useful to be able to measure this directly, especially if non standard amounts of illumination are required. The amount of UV should be as little as possible but in general should not exceed 20 mW/M².

A Lux readout is provided to control illumination and limit damage done by visible light. Normal museum light levels should be limited to 150-250 Lux.

764 Environmental Monitor

SPECIFICATIONS

Method of radiation detection	Twin silicon photodiodes connected to single chip microprocessor
Visible wavelength range	400-700nm (CIE response). No correction required for different light sources; spectral sensivity see here
Visible power range	0.1 - 200,000 Lux (0.1 – 20,000 Foot-candles)
UV wavelength range	300-400 nm, spectral sensivity see here
UV power range	2 - 50,000 mW/sqm
UV proportion range	8 - 10,000 mW/Lumen
RH sensor	Capacitive film type
RH range	0-100% RH
Display resolution	Lux: 0.1 up to 100 then 1 Foot-candles: 0.1 up to 100 then 1 UV: 0.1 up to 100 then 1 Proportion of UV: 1 mW/Lumen Temperature: 0.1° C or ° F RH: 0.1 %
Accuracy (manufacturer's data)	Light: 5% ± 1 displayed digit (the instrument has no classified accuracy) UV: 15% ± 1 displayed digit Temperature: ± 0.5° C (± 0.9° F) RH: ± 2.5% if newly calibrated
Angular response (Light & UV)	Cosine
Readout	8 line graphical Liquid Crystal Display with automatic backlight
Data logging time intervals (764C only) (Time till full)	10 seconds (30 hours), 1 minute (7½ days) , 10 minutes (75 days), 1 hour (454 days)
Data logging storage capacity	10,900 readings of all 4 parameters
Storage resolution for logged data (764C only)	Light & UV: 0.1% of saved value Temperature: 0.5°C Humidity: 0.5% RH
Computer Interface (764C only)	IrDA compatible wireless infrared link
Date function	Display as day-month-year or month-day-year.
Batteries	2 of alkaline AA type
Battery Life	Approx. 100 hours continuous use or 12,000 readings taking 30 seconds each. Battery life will be less if the display backlight is used
External Power Supply for 764C with option external power supply	4.0-5.2V DC, 100mA. A suitable mains power supply can be provided as an optional extra (please specify mains voltage required).
Operating Temperature	0-50°C
Dimensions	150 x 65 x 25mm (5.9 x 2.5 x 1 inches) including RH/temperature probe
Weight	165 g (5.6 oz) with batteries.

Environmental Monitor Type 764, measures visible light (Lux or Foot-candles), UV light (mW/m² and µW/lumen, temperature (°C or °F) and humidity (% RH) No longer available! The succeeding model ELSEC 765 is now in stock.	730,- €
Environmental Monitor/Logger Type 764C, as above with data logging capacity for over 10 000 readings of all 4 parameters, with wireless infra-red interface and Windows software	904,- €
Environmental Monitor Type 7640, measures only visible light (Lux or Foot-candles), UV light (mW/m² and µW/lumen, but no temperature and humidity.	620,- €
Environmental Monitor Type 774, measures visible light (Lux or Foot-candles), UV light (mW/m² and µW/lumen, IR-light and temperature (°C or °F) Not available any more until further notice	730,- €
Environmental Monitor/Logger Type 774C, as above with data logging capacity for over 10 000 readings of all 4 parameters, with wireless infra-red interface and Windows software Not available any more until further notice	904,- €

OPTIONAL EXTRAS

Humidity calibration kit for 764, manufacturer's version: metal calibration block, two bottles of dry salts, bottle of distilled water. The dry salts need to be dissolved before each use.	121,- €
Humidity calibration kit for 764, our low-cost version: two bottles of pre-mixed salt-solutions, ready for use. The necks of the bottles fit exactly around the sensor head of the ELSEC 764. One bottle of distilled water, one bottle of dry high purity MgCl2. We recommend this low-cost version, it is very practical.	25,- €
IrDA adapter for Windows, serial Com port RS 232 (software is integrated in your Windows system) or with USB-port (please specify)	24,- €
Universal Mains power supply (100 - 240V). Note: The instruments are supplied without a connection for an external supply unless specifically requested. External power connection (not normally required)	mains adaptor 25,- € mains connection 35,- €
	Order/Contact

Terms of sales and delivery

Products on stock are usually sent out within one week. Nevertheless, please order as early as possible. Transport is normally by UPS standard (±2-3 days within Europe), shipping and packing are billed with € 5,- + shipping costs, from € 200,- only the real shipping costs.
All prices are exclusive VAT. Payments can be made within 30 days by bank transfer, within 14 days with 3% discount. All prices are subject to change without prior notice according to our terms and conditions. Check our website for actual information.

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