Publicidad
V5969
Description
The RS pH meter is a low cost, high performance instrument with a
laboratory specification, covering the range 0pH to 14pH. The solid-
state electronics of the instrument are protected by a tough, chemical-
resistant plastic case, built to withstand industrial handling.
Although the pH meter is designed for use in a laboratory, its operating
simplicity and small size make it ideal for use in greenhouses, abattoirs,
plating plants, process works, darkrooms and boiler houses.
The large, clear 31⁄2 digit Liquid Crystal Display gives easy-to-read
figures to two decimal places.
A simple temperature compensation control and two calibration
controls are all that are needed to enable this meter to provide accurate
results from any combination type glass electrode (e.g. RS stock no.
205-075) or separate glass and reference electrodes.
Operation
Connect the pH probe to the instrument via the BNC socket situated on
the top of the instrument. The pH meter may be switched on by means
of a switch located on the left-hand side of the instrument.
The instrument should now be compensated for solution temperature.
This is achieved by turning the right-hand control marked temperature
to match the temperature of the solution under test or the buffer
solution. The other two controls are for electrode calibration. This is
simply done by immersing the electrode, to at least cover the porous
plug, in a standard 7pH buffer solution and adjusting the '7pH buffer'
calibration knob until the read out matches the known pH of the solution
at that temperature. The electrode is then removed from the 7pH buffer
solution, washed with distilled water, and immersed in a standard 4pH
buffer solution. The '4 or 9 slope' calibration knob is then adjusted until
the read out matches the known pH of the solution at that temperature.
Allow a few minutes for the reading to stabilise.
The two calibration controls are slightly interdependent, so the
calibration procedure should be repeated until the instrument reads
correctly in both solutions. For best accuracy, the buffer solutions
should be at the same temperature as the
solution to be tested.
Adjustment of the 'slope' control permits the use of electrodes having a
reduced sensitivity resulting from a normal ageing process. When it is
no longer possible to obtain the correct reading during standardisation,
the electrode requires replacement.
Preparation of a standard buffer solution from
pH buffer powders (RS Stock no. 654-865)
pH Buffer Powders
These Buffer Powders represent an important advance in the
preparation of standard solutions since they are accurate and dissolve
easily. The pure dry chemicals used are sealed into a colour coded
easy to open capsule, which keeps out moisture and gases that can
cause deterioration of the buffer powder. For best results a fresh buffer
solution should be made up on the day of use.
2
Directions
RS Stock No.
Empty the contents of the capsule into the vessel which will be used for
making up the solution, ensuring that all the powder is released into the
610-540
vessel. The water should be freshly distilled or demineralised. Distillate
from hard water may be heavily contaminated with carbon dioxide,
which should be removed by aeration or boiling prior to use. An
accuracy of 2% in the volume of water used is sufficient.
°C
pH4
pH7
pH9
Solutions have an accuracy of ±0.02pH at a temperature of 25°C.
The solution should not be used for calibration after the day on which it
is made up, but it may still be used for probe storage.
Technical Specification
Measurement range __________________________0.00 to 14.00pH
Resolution ________________________________________0.01pH
Repeatability ______________________________________±0.02pH
Accuracy ________________________________________±0.03pH
Electrode temperature compensation ______________-5°C to +70°C
Operating temperature range ______________________0°C to 45°C
Input current1 ______________________________________pA (typ)
Input resistance ________________________________1012 Ω (typ)
Display ________________________12.7 mm Liquid Crystal Display
Battery ____________________________________9 volt type PP3
Instrument case ____________________________________A.B.S.
Dimensions ________________________________110 x 68 x 34mm
Weight (inc. battery) __________________________________220g
RS Components shall not be liable for any liability or loss of any nature (howsoever
caused and whether or not due to RS Components' negligence) which may result
from the use of any information provided in RS technical literature.
10
15
20
25
3.99
4.00
4.00 4.00
4.00 4.01 4.02 4.05 4.07
7.07
7.04
7.02 7.00
6.99 6.98 6.97 6.96 6.96
9.21
9.14
9.06 9.00
8.96 8.92 8.88 8.83 8.81
30
35
40
50
60
Publicidad
