Valve Paper Bags — PVSE, PBOM and SOM
A valve sack lets you fill a 25kg bag of powder in two seconds without dust and without closing it afterwards. We manufacture pasted valve bags with a sewn easy-open end (PVSE), pasted bottom open mouth (PBOM) and sewn open mouth (SOM) sacks for cement, mortar, flour, chemicals and dry mixes.
Click a thumbnail to change the view, or the photo itself to enlarge it.
Why filling lines are built around valve bags
On a valve filling line the nozzle pushes through the valve, product flows in under pressure, and when the bag leaves the nozzle the internal pressure closes the valve against itself. Nothing has to be sewn or glued afterwards and very little product escapes into the air. For powders such as cement, gypsum, tile adhesive, flour and chemical additives that is worth a great deal: less dust, less waste, a cleaner plant and a much higher filling rate.
The trade-off is that valve filling equipment is less forgiving of a badly specified bag. Valve position, valve patch size and the stiffness of the ply structure all have to match your machine. That is why we ask for your filling equipment details, and why we make a sample on the same line that will run your order.
The four constructions we produce
| PVSE | Pasted valve with sewn easy-open end. Filled through the valve; the customer opens it along the sewn edge with a tear strip or knife. The standard sack for cement, mortar and chemical powders. |
|---|---|
| PBOM | Pasted bottom open mouth. Filled from the top, then closed by the customer. Good for granules and products filled by weight on semi-automatic lines. |
| SOM | Sewn open mouth. Filled and then closed with thread on a sewing line. The most flexible construction for varying fill weights. |
| Block bottom (SOS) | A folded block base so the bag stands upright on a shelf. Best print face and retail presentation. |
Options
- 2 to 5 plies, kraft brown or bleached white
- PE film, aluminium foil or PP laminated barrier plies
- Grease resistant inner ply for oily or fatty products
- Anti-skid treatment for pallet stability
- Micro perforations where the product must breathe
- Flexo printing up to 6 colours on a flat, high detail face
- Food grade and UN certified constructions on request
Valve bag FAQ
Can you match the valve to my filling machine?
Yes, and we need to know the machine make and model, the filling nozzle diameter and the fill weight before we quote. Send a photo of the nozzle and of your current bag and we will confirm the valve specification.
How much does the bag weigh when empty?
It depends on the ply count, the paper grammage and the size, but a 25kg three-ply 500 × 800mm sack typically weighs 150 to 220g. We will give you the exact figure with the quotation so you can calculate freight and material cost per tonne.
What is the minimum order for printed valve bags?
Because printing requires cylinders, the economic minimum is usually one 20ft container for a custom printed design. We do support low minimum order quantities for a first order so you can trial the quality before committing to volume — ask us what applies to your specification.
Send us your filler details and we will specify the sack
Filling machine, nozzle diameter, fill weight, product and destination. That is enough for us to quote an accurate valve sack.
- Emailsales@unisunpack.com
- Tel / WhatsApp+86 15825665852
- FactoryWenzhou, Zhejiang Province, China 325000
- Response timeWithin 24 hours, Monday to Saturday
