Proper Vacuum Receiver Selection Impacts Central System Operation
Vacuum receivers are an integral part of any central conveying system. As such, it is important to understand:
- Types of receivers
- Basic receiver features
- How receivers operate
- Troubleshooting procedures
Vacuum receivers, also called vacuum chambers, vacuum stations, or just stations, are integral parts of a central conveying system. Think of them as intermediate holding points for resins conveyed by vacuum. Vacuum receivers have one primary job: separate material from air. They accept resin from a source that is pulled by vacuum, separate the material from the air flow and transfer that resin to a destination.
Vacuum receivers come in several designs with all sorts of features aimed at offering a variety of advantages in conveyance, maintenance, and ease of use. Some receivers are designed for pellets, some for regrind, and others for powders.
Some receivers mount atop hoppers or bins; others are mounted directly to the throat of a processing machine.
All receivers have a sequencing device. Some receivers require a separate sequencing valve to connect to the vacuum line; others have a built-in fill valve. The sequencing device allows vacuum to pull material into the receiver and while the bulk of the material falls to the bottom of the receiver, the vacuum pulls the air up through the top of the receiver and back to the vacuum pump.
Most dust and fines are trapped by a filter but there are also Filterless Receivers.
Receivers come in various capacities, from small (1.5 lb.), to medium (75 lb.), to large (114 lb. and more). The multitude of designs, capacities, and feature sets is what makes it possible to specify a vacuum receiver that perfectly matches the needs of a plastics conveying system.
More on Filterless receivers:
There are two distinct styles of filterless vacuum receivers. The “removeable-lid’ receivers require a separate vacuum sequencing valve (“T” valve) while the very popular hinged-lid models that have a built-in sequencing valve.
In either case, going filterless eliminates the necessity of cleaning filters and the filter replacement costs. A filter is not required because these models use a cyclonic action to separate the material from the air flow. In addition, a Blowback option is not required so that cost is eliminated.
There are other features that should be considered like; a stainless steel body which provides an attractive scratch-resistant surface; a tangential material inlet with a gasketed check valve that minimizes degradation of material while also minimizing harm to the receiver walls.
The hinged lid models are popular because the lid swings up and locks in place so the interior of the receiver can be safely cleaned after material changes. Some also have a local ON/OFF switch so the operator does not have to walk to a central control to turn the unit OFF.
When conveying particularly abrasive materials, either style is available with extended wear ceramic coated options that are bolted in place and can be replaced, when necessary.
The removable lid models are available in capacities of 1/3 to 3 ft3 while the hinged lid models are available from 1/3 to 2 ft3. Machine mount styles are available with multiple glass sizes for most models.