US 5,872,721 A · Monitor-control systems and methods for monitoring and controlling atmospheres in containers for respiring perishables

Abstract

A system adapted for removable placement in a security enclosure fitted into the wall of a refrigerated container for respiring perishables, and for monitoring and controlling, continuously and dynamically, over a programmed, desired time, the concentration of oxygen, and the concentration of dioxide, in such a container atmosphere where the concentrations of these gases vary over time as the perishables respire, includes devices for sensing, separately, the concentrations of oxygen and carbon dioxide in the container atmosphere, devices for establishing setpoints or desired values of oxygen and carbon dioxide atmospheric concentration within the container, and for changing those setpoints, over time, depending on the nature of the perishable and other variables, and for maintaining the atmospheric concentrations of oxygen and carbon dioxide at desired setpoints for desired programmed times by admitting outside air into the container, as a source of oxygen, and by scrubbing to remove carbon dioxide, as necessary.

Claims27

Dependent claims

An apparatus for determining the concentration of carbon dioxide in a gas mixture that includes carbon dioxide, comprising:

housing means forming a chamber permeable to gas mixtures and carbon dioxide;
mounted within said housing in said chamber, a container having two chambers, with the first of said chambers substantially impermeable to gases entering said space, the second of said chambers having an opening to admit gases entering said chamber;
each of said chambers including a thermistor, said thermistors being adapted to be maintained at substantially the same current;
and means for detecting signals from said thermistors to determine said carbon dioxide concentration.

1 more element

A system for controlling the oxygen and carbon dioxide concentrations in a refrigerated container for respiring perishables, comprising:

an enclosure means;
a controller suitable for being placed in and removed from said enclosure means, said enclosure means having a size and shape suitable for installation in an exterior wall of said refrigerated container to provide gas access to the refrigerated air stream inside said container and to provide gas access from the exterior of said container, said controller comprising:
means including an oxygen gas sensor for dynamically and continuously monitoring the oxygen gas concentration in said container;
and
means including a carbon dioxide gas sensor for dynamically and continuously monitoring the carbon dioxide gas concentration in said container,
said oxygen and carbon dioxide monitoring means being connected to means programmed to maintain desired levels of oxygen and carbon dioxide in the refrigerated container by activating valve means to admit atmospheric air as a source of oxygen into said container and to expel from said container gases low in oxygen concentration and high in carbon dioxide concentration to thereby dynamically and continuously control the oxygen gas and carbon dioxide gas concentrations in the refrigerated container.

3 more elements

Dependencies are inferred from the claim text.

Monitor-control systems and methods for monitoring and controlling atmospheres in containers for respiring perishables

Life of this patent

Monitor-control systems and methods for monitoring and controlling atmospheres in containers for respiring perishables

Life of this patent

Abstract

Claims27