Cylindrical Piston Purged Sampling Sensor

Introduction

Sensortech Systems, Inc. has recently expanded the range of ST2200A series moisture sensors with the addition of a 6" diameter sampling sensor. Designed specifically for the wood products industry, the large sample volume provides a bulk average moisture, less affected by particle shape and size.

Description

A fiberglass lined sampling chamber collects product during the "fill time" interval programmed in the instrument processor (1-99 second). A one second moisture measurement is taken after fill time expiration. Instrument displays last sample until updated on next cycle. Following measurement, a pneumatic ram purges the measurement chamber, returning product to the mainstream. A rotary brush surrounds the purge piston, cleaning sample chamber on each actuation. Various mounting flanges are available to suit application, including oblique flange for inclined chutes and drag conveyors, saddle flange for screw conveyors and flat flange. Oblique flanged sensor has side air purge to supplement product clearance (see figure 1). Sensor electrode is integrated into sample chamber. Sensor electronics and pneumatic controls are attached to sensor assembly. Entire sensor assembly connects to instrument processor via multi-conductor shielded cable.

Physical

Applications

1. OSB wafers, before and after drying.

2. MDF fiber before forming line.

3. Wood chips

4. Sawdust

5. Most free flowing granular or fibrous materials.

Figure 1 - Piston Retracted

Figure 1 shows sampling sensor with oblique flange mount for incline chute application. Piston is retracted during programmed "fill time" interval.

Figure 2 - Piston Extended

After taking moisture measurement, the piston purges sample chamber and side air blast removes residual product from piston face.

Figure 3

Figure 3 demonstrates the use of sampling sensor in a screw auger application.