To create a flexible doorway, one that’ll wholly protect a coolroom, the barrier material must demonstrate one primary feature. Dropping from threshold ceiling to the floor, from the entryway’s left side all the way to the right frame edge, the chosen material has to hang straight. Thick enough to assure a straight-edged seal, transparent vinyl plastic strip curtains use their dense materials to prevent cross-contamination incidents.
Reinforced PVC Density
Sticking with flexible PVC (Poly-Vinyl Chloride), this rugged plastic stays straight and hard-wearing as long as it’s manufactured in thick rolls. If the plastic’s thickness drops well below 1mm, well, the material curves and warps. In doing so, it’s no longer dense enough to hang straight. Subsequently, a threshold seal is compromised. In this instance, the plasticity of the polymer has prevailed, and a plastic strip curtain can no longer retain enough resiliency, enough solidity, to establish a coolroom’s seal. Furthermore, this barrier doesn’t possess any insulating properties. It’s a seal in name only. To watch it in action, it curls and deforms whenever a breeze rises, and it’ll tear as soon as a pallet truck pushes between the overlapping strips.
Cohesive Hanging Plastic Strips
Because of a nominated plastic’s malleability characteristics, it turns limp and abominably flaccid when it’s manufactured as an overly thin roll. It’s formed into plastic strip curtains, which do feature a high degree of material transparency, but their sealing qualities are less than impressive. Over 1mm thick, more commonly manufactured as 3mm to 5mm thick plastic sheets, the thickness of these more durable strips adds a healthy quantity of material density to the product line. Now, with the plastic strip curtains hanging sturdily, an incorruptible seal forms.
Dealing With Negative Pressure Problems
This flexible entryway configuration has been covered in past posts. We’ve talked about thickness-imbued material insulation, about cross-contamination prevention methods, and about transparency benefits. People and vehicles slip through the curtains safely and easily when these qualities are assessed properly. Here’s another problem, one that disappears when thicker PVC strip curtains are fitted. Simply put, air currents cool when a coolroom is refrigerated. The molecules of the air draw closer. When this happens, negative pressures develop. Fortunately, a dense array of strips defeats such pressure-related complications.
Still thinking about that last issue, everyone has seen this situation crop up at home. On pulling a refrigerator’s door open, there’s resistance. This is because of negative pressure, plus a slightly magnetic door seal. In walk-in coolrooms, this vacuum-like effect forces thin materials to curve and bow inwards. Thankfully, by assuring a minimum thickness, plastic strip curtains easily resist this nuisance effect.