• System check of OxiTop® systems with 10 calibration tablets for checking measuring units (long term test of leakage testing and negative pressure).

The usage of the OxiTop PM tablets is only supported for the normal BOD configuration with brown sample bottle PF 600, 510 ml total volume and OxiTop head.

What you can do is to calculate the equimolar mass (n) of oxygen consumption reagent of one OxiTop PM tablet with the common gas equation (p * V = n * R * T) and use the result on an individual system.

For example:

n = [p * V] / [R * T]

p = pressure result in hPa (31 digit * 3,55 hPa per digit (see the attached calibration certificate of an OxiTop head) = 110 hPa)

V = gas volume in liter in the sample bottle for the determination (0.510 L total volume – 0.164 L water) = 0.346 L  

R = gas constant = 83,14

T = temperature in Kelvin for 20 °C = 293

n = [110 * 0.346] / [83.14 * 293] = 0,00156 mol

Now you can calculate the result for a sample bottle with 1 L using 0.164 L water as sample (for example):

p = [n * R * T] / V

p = [0.00156 * 83.14 * 293] / (1 L – 0.164 L ) = 45.5

The expected result is 45.5 hPa.

If you need the result for a normal OxiTop head in digit, divide the result with 3.55:

45.5 / 3.55 = 13 digit.

Using 2 tablets double the result.

For the calculation you need exact volumes. Usually the exact volume of a laboratory bottle with nominal volume of 1 L is more than 1 L.