Self-closing valve design engineered for high-speed automated filling of fine powders — no separate closing equipment required.
The valve construction is specifically engineered for fine and semi-fine dry powders with good flowability. Cement, dry-mix mortar, tile adhesive, plaster, flour, and mineral powders are the primary applications. Valve dimensions are matched to filling spout diameter and product flow characteristics — standard internal valve diameters range from 95 to 140 mm. Sackora configures valve length, position (left or right corner), and material (kraft paper or PP woven) to match your specific packer model and product requirements.
The pre-closed bag construction means product is fully enclosed after filling with no exposed open top, providing superior dust containment compared to open mouth designs. This is critical in facilities subject to occupational dust exposure limits and in applications where product loss from dusting represents measurable waste. PE lamination on the inner surface is standard for cement and hygroscopic products.
Available Sizes
Click any size below for full specifications, or request a custom size.
All specifications are fully customizable. Contact us to discuss your exact requirements.
| Material | Woven Polypropylene (PP) |
|---|---|
| Fabric Weight | 70 – 110 GSM |
| Dimensions (W × L) | 40 × 60 cm to 55 × 85 cm |
| Load Capacity | 20 – 50 kg |
| Valve Type | Internal sleeve — kraft paper or woven PP |
| Valve Diameter | 95 – 140 mm (matched to packer spout) |
| Valve Position | Top left or top right corner |
| Lamination | PE inner lamination (standard for cement/powder) |
| Printing | Up to 4-colour flexographic |
| Filling Speed | 1,200 – 2,400 bags/hour (packer dependent) |
Valve top bags are the industry standard for Portland cement, masonry cement, tile adhesive, grout, and pre-mixed stucco in 20–40 kg packs. The self-closing valve minimizes airborne cement dust on the packing line and eliminates the cost and maintenance of bag sewing equipment. PE lamination prevents moisture absorption during warehouse and outdoor storage.
Industrial flour mills and starch processors use valve bags for 20–25 kg packs destined for bakeries and food manufacturers. The enclosed bag design reduces flour dust, improving facility air quality and reducing product loss. Food-grade valve bags are manufactured from virgin PP in certified facilities to meet CFIA and FDA requirements.
Calcium carbonate, talc, kaolin, titanium dioxide, and agricultural lime are packed in valve bags on high-speed rotary fillers. The valve format enables consistent fill weights with powder-specific auger or air-packer filling systems, and the laminated construction protects moisture-sensitive chemical products throughout the distribution chain.
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Learn More →The valve is a flat tube sewn into the top corner of the bag. During filling, the product flows through the valve opening. Once the bag is removed from the filling spout and laid flat, the weight of the product compresses the valve tube flat, creating a friction seal. The internal product pressure holds the valve closed. For additional security on very fine powders, heat-sealable valve materials or valve flaps with adhesive strips are available.
Valve bags are designed for automated packing systems including Haver & Boecker, Behn Bates, Chronos Richardson (BW Flexible Systems), Concetti, Payper, and similar rotary carousel and inline impeller or auger fillers. Sackora matches valve dimensions to your specific packer model to ensure proper fit and seal performance.
Valve bags are optimized for fine to semi-fine powders with particle sizes below approximately 500 microns. Coarser granular products may not flow reliably through the valve sleeve and can prevent proper valve closure. For granular products like fertilizer pellets or plastic resin, open mouth bags with sewn closure are typically the better specification.
A kraft paper valve is the traditional design, offering excellent friction seal properties. A woven PP valve is more durable and moisture-resistant, making it the preferred choice for outdoor-stored products like cement. PP valves also offer better longevity on high-speed rotary packers where valve wear from repeated spout contact can shorten paper valve life.
Valve top PP woven bags are recyclable as Type 5 polypropylene through industrial recycling channels. Due to the enclosed design, they are not typically reused for refilling. However, spent bags can be collected and baled for recycling into secondary PP products. Sackora can advise on recycling programs available in your region.
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