£389

Deluxe pH / ORP / Cond / TDS / Salt / DO / O2 Meter

Deluxe pH Meter

Features:
1. Microprocessor based designed, and rugged housing with splash proof keyboard.
2. The large backlight LCD displays pH or ORP or Conductivity or DO and Temperature simultaneously.
3. Automatic Temperature Compensation(ATC), Manual Salinity(MSC) and Altitude(MAC) Compensation.
4. Memory function stores and recalls up to 150 points. MAX/MIN and data Lock. Degree ℃/℉ are switchable.
5. Combine special platform and electrode holder, or stirrer(Optional) for measuring convenient.
6. The TDS value is determined by multiplying a conductivity reading by a known ratio in the range of 0.50 to 1.00.
7. Output data for capturing on PC directly via USB.

BenchTop pH Meter

Specifications:

BenchTop pH Meter
	pH	ORP
Range	-2.00~16.00 pH	-1999 ~ -200 mV -199.9 ~ 499.9 mV 500 ~ 2000 mV
Accuracy	±0.01+1 digit	±2+1 digit
Resolution	0.01 pH	0.1/1 mV
Compensation	ATC: 0~100 ℃	N/A

	Conductivity	TDS	Salt
Range	0.0~ 199.9μS 200~ 1999μS 2.00~ 19.99 mS 20.0~ 100.0 mS	0.0~131.9 ppm 132~1319 ppm 1.32~13.19 ppt 13.2~66.0 ppt	0.0~99.9 ppm 100~999 ppm 1.00~9.99 ppt 10.0~50.0 ppt
Accuracy	±2% FS	±2% FS	±2% FS
Resolution	0.1/1μS/0.01/0.1 mS	0.1/1ppm/0.01/0.1ppt	0.1/1ppm/0.01/0.1ppt
Compensation	ATC: 0~50 ℃	ATC: 0~50 ℃	ATC: 0~50 ℃

	DO	O2	Temp.
Range	0~20.00 mg/L 0~20.00 ppm	0~200.0 %	0~110 ℃
Accuracy	±0.2+1 digit	±2% FS	±0.2+1 digit
Resolution	0.01 mg/L	0.10%	0.1 ℃
Compensation	ATC: 0~50 ℃ MSC: 0~50 ppt MAC:0-20000 ft

Guide to Conductivity Measurement

Electrical Conductivity is the ability of a solution to transfer (conduct) electric current. It is the reciprocal of electrical resistivity (ohms). Therefore conductivity is used to measure the concentration of dissolved solids which have been ionized in a polar solution such as water. The unit of measurement commonly used is one millionth of a Siemen per centimeter (micro-Siemens per centimeter or µS/cm). When measuring more concentrated solutions, the units are expressed as milli-Siemens/cm (mS/cm) i.e.- 10-3 S-cm (thousandths of a Siemen). For ease of expression, 1000 µS/cm are equal to 1 mS/cm. Often times conductivity is simply expressed as either micro or milli Siemens. However this unit of measurement is sometimes (incorrectly) referred to as micro-mho's rather than micro-Siemens. The expression "mho" was simply the word ohm spelled backwards.

Several means of conductivity expression have been adopted by various industries as a way of making the units of expression into whole numbers. The water softening industry refers to "grains" of hardness and uses TDS or total dissolved solids as a measurement scale. While TDS is really a gravimetric measurement, because in solution the solids are predominately present in ionic form, they can be approximated with conductivity. The TDS scale uses 2 µS/cm = 1 ppm (part per million as CaCO3). It is also expressed as 1 mg/l TDS. While the method of measurement is the same, some conductivity meters can make the conversion and express the results of a measurement in many different units. This is helpful for users who are accustomed to one particular unit of measurement.

Table of Aqueous Conductivities
Solution µS/cm mS/cm ppm
Totally pure water 0.055
Typical DI water 0.1
Distilled water 0.5
RO water 50-100 25-50
Domestic "tap" water 500-800 0.5-0.8 250-400
Potable water (max) 1055 1.055 528
Sea water 56,000 56 28,000
Brackish water 100,000 100 50,000

Conductivity/TDS

Electrical Conductivity sensors are used to measure the ability of water to carry an electrical current. Absolutely pure water is a poor conductor of electricity. Water shows significant conductivity when dissolved salts are present. Over most ranges, the amount of conductivity is directly proportional to the amount of salts dissolved in the water.

The amount of mineral and salt impurities in the water is called total dissolved solids (TDS). TDS is measured in parts per million. TDS tell how many units of impurities there are for one million units of water. For example, drinking water should be less than 500 ppm, water for agriculture should be less than 1200 ppm, and high tech manufactures often require impurity-free water. One way to measure impurities in water is to measure the electric conductivity of water.

A conductivity sensor measures how much electricity is being conducted through a centimeter of water. Specific conductivity is expressed as mhos per centimeter (M/cm), sometimes called siemens per centimeter (S/cm). Because a mho (or siemen) is a very large unit, the micromho (microsiemen) or millimho (millisiemen) typically is used (mS/cm).

To convert the electric conductivity of a water sample (mS/cm) into the approximate concentration of total dissolved solids (ppm), the mS/cm is multiplied by a conversion factor. The conversion factor depends on the chemical composition of the TDS and can very between 0.54 – 0.96. A value of 0.67 is commonly used as an approximation if the actual factor is not known [(TDS)ppm = Conductivity µS/cm x 0.67].

Since conductivity varies with temperature, it is necessary to correct the readings for changes in temperature. Most instruments contain circuits that automatically compensate for temperature and correct the readings to a standard 25°C.

Water purity varies widely. Therefore, Greenspan offers conductivity ranges from 0 – 70,000 µS/cm.

Operating manual