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| Oxygen Probe Manual | Data sheet | News Letter | buy or view price |
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The most Robust Accurate and Low Cost probe available The oxygen probe is a very high performance and extremely robust oxygen probe manufactured by Dryden Aqua for the measurement of oxygen in water and air. The probe provides for a low cost, easy maintenance sensor suitable for connection to Dryden Aqua monitors ( AquaTraul), or your own instrumentation. The probe has a high mv out-put for PLC based controllers, the high out-put increases accuracy and reduces electrical noise problems. The unique shape provides a streamlined approach. Reference of the Dryden probe used in research Typical Applications
Technical Properties The oxygen probe is a galvanic cell, basically the probe acts like a battery in which there are two dissimilar metals in a conducting electrolyte solution. The anode is zinc and the cathode is silver, oxidation takes place on the surface of the anode to form a white deposit of zinc oxide. The rate of oxidation is a function of the diffusion of oxygen through a semi permeable Teflon membrane, which is in turn directly related to the partial pressure of oxygen in solution, or in the air. A potential difference is established in the probe, the milli volt out-put being approx. 6mv per 1 mg/l of dissolved oxygen. This gives the probe a reading of approximately 60mv when in air. Any length of good quality two core ( 0.5mm squ, multi-strand) cable can be connected to the probe, technically there is no limit to the length of cable that you can attach, however we have only tested to 2000 meters. General maintenance is also very easy, all that you need to do is keep the probe membrane reasonably clean, this is achieved by giving the membrane a wipe with a cloth once a week.
Transmitter turns probe into a full blown Oxygen meter 4 to 20mamp transmitter and Oxygen meter with 2 x alarms outputs The Dryden Aqua DIN rail mounted oxygen transmitter will accept an input directly from our Oxygen Probes. The transmitter can then send the value back out as a voltage ( e.g. 0 to 10v) or analogue out-put, (0 to 20mamps, or 4 to 20mamps) The transmitters are provided with a clip on front display which is used to program the transmitter for different functions. The display gives the raw data out-put from the oxygen probe. It is useful to display the raw data, especially if you are using PLC based systems. The display can also be used to calibrated the unit to display the data as dissolved oxygen. This makes for a very low cost multi-channel dissolved oxygen monitor. The transmitters clip onto a standard DIN rail, so all you need to do is purchase the oxygen probes and transmitters from Dryden Aqua and fit the transmitters into a box. The Oxygen probes connect directly onto each transmitter Transmitter model 4116 has the same specifications, but also includes two relay out-puts that can be programmed
Clip on display provided with the transmitters gives a direct reading of the out-put from the probe in milli volts or mg/l of oxygen |
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Oxygen meter on a budget
If you have a requirement for occasional measurements of oxygen but don't want to go to the expensive of buying a full instrument, then you can actually do it on a low budget.
1. Purchase an oxygen probe from Dryden Aqua, click here
2. Purchase a low cost milli-volt meter from you local DIY or electrical store for about 20 Euro
3. Measure the milli-volt out-put from the probe with the probe in air, also measure the air temperature, example lets say air temp is 15.5 deg C
4. The probe out-put is approx 8mv per mg/l of oxygen, so it should give a reading of around 80mv +/- 20mv with the probe in air. Take a note of the probe reading in milli volts, lets say it is 85mv
5. Look up the oxygen solubility table in the probe manual Oxygen Probe Manual
6. From the Oxygen solubility Table, for the value corresponding to the air temp 15.5 deg C as our example. = 9.96 mg/l of oxygen
7. You now know that 9.96mg/l of oxygen = 85mv, so 1 mg/l of oxygen = 85/9.96 = 8.53 mv
8. You can now put the probe in the water, leave it for a few minutes to stabilise, read the mv out-put, lets say it now reads 55 mv. The oxygen concentration is 55/8.53 = 6.45 mg/l of dissolved oxygen
9. If you wish to measure in % saturation, then this can also be done, but you need to use a different type of membrane on the oxygen probe.