7
For maximum clarity and ease of interpreting the graph you should choose the
starting point and step sizes from the numbers 0, 1, 2, 5, 10, 20, 50 etc. The starting
point can be a negative number but the step size must be positive.
The total span of each scale will depend on the step size you choose and the
number of major divisions that fit onto a page. This depends on the graph style (see
below) and the paper size you are using. Remember that the scales run across the
shortest dimension of the page.
Choose the graph style.
You can choose inch or metric sizes with major graph divisions of one inch or 20
millimetres. Fewer major divisions will fit onto the page with the inch size but the
graph will have greater resolution and therefore show slightly more detail.
You can also choose the type of grid that is printed as a background to the graph.
The standard grid with major divisions and tenths accurately divides each grid
square into tenths and makes the graph easier to interpret. Turning the grid off
completely will result in slightly faster graph printing in most cases.
Head space correction
Monitors that measure pressure in cans and bottles use a pressure sensor inside the
instrument that connects to the container via a quick release coupling and a fine
flexible tube. This inevitably causes a slight increase in volume which slightly
disturbs the pressure in the container. If the theoretical volume of the head space of
the container is known and entered into the RPC-80 then the unit can make a first
order correction for the error. The pressure sensor connections must be cleaned out
after each run so that the pipe and coupling are empty if this error correction is to
operate correctly. The error is only significant when head space volume is less than
about 20 millilitres. The maximum correction allowed will increase the recorded
pressure by 5%. You may choose not to make this correction if you use many
different sizes of container and print all the results with one RPC-80.
H
EAD
S
PACE
C
ORRECTION
? allows you to choose whether to make the correction.
H
EAD
S
PACE
V
OLUME
allows you to set the theoretical volume in millilitres (same as
cubic centimetres).
The correction will be applied to printed output, displays and pre-processed data
output on the External Link from the pressure channel of all 200 & 300 series PU
monitors used with this playback unit. If you choose to make this correction then the
head space volume will be printed on the results page with the pressure channel
results.