TGM stands for Targeted Grain Management.  TGM enables you to target your desired outcome and achieve this economically, with less worry and attention, and with precision so you deliver grain of higher quality, purity, and value.

The moisture content (”MC”) in grain after harvest impacts storability, usefulness, and value.  Over dry grain weighs less, is more brittle, and is less palatable.  In general a higher moisture content increases usefulness but too high increases risk of mold growth and insect activity.  There is a narrow band of MC that delivers maximum returns.  The Sentry PAC®  aeration controller keeps your grain in this band - and helps get it to this sweet spot by either removing or adding moisture over time.

The Problem:  The largest cause of spoilage in grain is moisture migration.  This occurs when the grain temperature is different from the average outside temperature.  Keeping grain near the average outside temperature prevents  moisture migration.

How does the PAC operate?  The PAC uses a running 21 day average temperature as a targeted temperature.  The high and low ends are limited to keep grain cooler in summer and to not get colder than necessary in winter.  The relative humidity (RH) of the outside air is included in the decision so MC can be regulated at the same time.

A temperature band (+/- range) around the targeted temperature and a moisture band around your Targeted Moisture Content (TMC) are established.  It checks every fifteen minutes  to see if the temperature is within the band.  If it is, it checks to see if RH will produce your TMC.  If it will, the fans are turned on.  This repeats every fifteen minutes so the fans will continue to run until conditions change or the backlog hours go to 0.

The bands are increased or decreased automatically by the size of the backlog of unused run hours.  Each midnight your budgeted run time is added to the backlog.  Fan runtime is subtracted.  If no run time occurs for awhile, the bands are widened to make fan operation  more likely.  After running the bands are narrowed to become "fussier".  This action is somewhat like a governor, always picking the best air available - optimizing for you even while you sleep.

Prevention instead of reaction.  It is common to run fans when grain starts to heat.  This is too late.  Instead, the PAC is both proactive and adaptive.  If you set something in your refrigerator you can predict when it will be cold.  Likewise, grain will equilibrate with the air surrounding it.  By running fans when  the right combination of temperature and RH is available the grain can be controlled so heating never starts.  The PAC adapts to the weather automatically.

Part of the success of the PAC is the frequency of fan operation.  Because conditions of the outside air will be nearly identical to the last time fans ran no fronts are introduced and the effect is to provide 'freshening'  that prevents problems from starting.

The PAC is easy to install and use.  Installation can be accomplished by yourself or your electrician.  Setting (no programming is necessary) consists of 4 basic steps:

Many options and features are available but these do not need to be used for basic operation.  Some examples are time of day lockouts, different modes for special cases, and a log of run times for the last 28 days so you can review operations after being away. 

An old saying is "Rain Makes Grain".  Farmers are intimately familiar with liquid water and its importance.  Dew formation, fast dry down, or a muggy day illustrate the impact of water in the vapor phase.  The amount of water vapor present with air is best understood and measured as relative humidity (RH).

The mean amount of water vapor over the whole earth is an estimated 1 inch of rain.  The residence time from evaporation to condensation is approximately ten days.  This resource is available for superior grain management.

Liquid water is managed with pumps and valves.  The PAC enables management of the MC of grain by selecting run times when the water vapor content of air will  move it to your TMC, then maintain that MC.  If grain is dryer it will gradually adsorb moisture, climbing only to your setting - legally.  If grain is wetter it will gradually desorb moisture without over drying the bottom.  Grain comes to equilibrium with the flow of air through it regardless if the flow is intermittent as long as air conditions are close to the last time fans were operated.  This achieves uniformity.  Also less energy is used and fronts are not introduced like is experienced with periodic, continuous operation strategies.

Advanced technology under development since 1995 is now used in the Sentry PAC® to provide high accuracy, full range 0-100% RH measurement (5% - 99% is displayed in the PAC).  This new sensor survives condensing  and has  a much higher  life expectancy since it is immune to the electrical issues that compromise others.  The technology is recognized by NASA and CERN as superior and more robust for field applications.  This means more precise regulation of fans and the ability to fine tune run times so energy can be saved without risking spoilage.

Sentry PAC models

GDD stands for growing degree days.  Up to four fields can be entered and the heat units will be calculated YTD. 

A program can manage 1 or more bins.  The criteria is each bin on a program should have the same grain, the TMC setting should apply to each, and the CFM per bushel should be close.

Optional temperature probes are available to insert into the top grain.  Up to 3 probes can be attached to each PAC.  The probes can be set to display temperature only or to trigger overrides.