For 25 kg open-mouth bagging, a single-spout net-weigh scale lines out at roughly 450-900 bags/hour, while a twin-spout (dual fill-head) configuration pushes the same 25 kg target to 1,000-1,800 bags/hour on the same bag weight class [S2][S4].
Those numbers come from the published curves of the CHRONOS OMP-B series (single-spout OMP-1045 B at 450 bags/hour, twin-spout OMP-2090 B at 900 bags/hour) and PAYPER's six-model 5-25 kg lineup that tops out at 1,800 bags/hour across the open-mouth class [S2][S4]. Manual bag placing on the same hardware drops throughput to 30-60 bags/hour, so the scale architecture, not the bag weight, is the dominant throughput lever [S7].
Single-Spout 25 kg Throughput: Where It Lines Out
A single-spout 25 kg net-weigh open-mouth system runs 450-900 bags/hour on the OEM data sheets, with the lower end typical of semi-automatic bag placing and the upper end reached with an automatic bag placer on a stable granule [S3][S5]. EWINALL's DCS-50FB3 dual-hopper net-weigh scale, for example, is published at 660-1,080 bags/hour across 5-25 kg, with the 25 kg corner of that range tracking closer to 660 bags/hour under real product conditions [S3].
For free-flowing 25 kg products (grain, fertilizer granules, plastic pellets, sugar, salt), the 25 mm typical fill-spout and single-screw or gravity feeder on a single-spout machine is rarely the bottleneck. The constraint is operator cycle time on semi-automatic rigs, then bag-placer pick rate once the placer is added. Inpak Systems' published manual bagger baseline of 5-10 bags/minute (300-600 bags/hour) is consistent with the operator-paced floor for 25 kg single-spout work [S5]. The Premier Tech Chronos OMP-1045 B hits 450 bags/hour with one screw feeder and a 480-bag magazine, which is the realistic single-spout ceiling for fine powders at 25 kg [S2].
Twin-Spout 25 kg Throughput: What the Second Head Buys
Adding a second fill spout and second weigh hopper roughly doubles throughput, with published twin-spout rates of 900-1,800 bags/hour at 25 kg depending on feeder type, bag-placer integration, and product flowability [S2][S4][S8]. The OMP-2090 B with two screw feeders hits 900 bags/hour on flour and fine powders at 25 kg, a class where dust control and accurate cut-off (rather than spout count) cap speed [S2].
PAYPER's open-mouth lineup extends twin-spout performance to 1,800 bags/hour in the 5-25 kg range, typically on a net-weigh scale with dual-screw discharge feeding two independent bag clamps [S4]. Concetti's IGF 600, paired with a fully automatic bag placer for PE readymade open-mouth bags, hits 600 bags/hour as a single-spout reference; the same architecture on a twin head is the typical 1,000+ bags/hour workhorse for 25 kg PE and woven PP bags in European chemical and mineral plants [S8]. The mechanical reality is that the second head adds cost linearly (second weigh hopper, second clamp, second sealing station) but doubles the only real serial bottleneck in the line.
Accuracy and Bag Weight at 25 kg: What Stays the Same
Accuracy is set by the weighing method, not the spout count, and a properly specified net-weigh scale delivers ±50-100 g at 25 kg regardless of whether one or two heads are running [S2][S3]. The OMP-B series is published at ±50 g at 2 sigma for 25 kg bags, which is the tight end of the range for flour and free-flowing powders [S2]. EWINALL's DCS-50FB3 dual-hopper net-weigh scale is published at ±0.1% of full scale, which on a 25 kg target works out to ±25 g at the controller but ±50-100 g under real plant conditions once product variability is included [S3].
Tinsley's mechanical Model 190, the reference low-end open-mouth bagger for granular products, runs at ±4 oz (100 g) on 50 lb (22.7 kg) bags, so the 100 g figure is a reasonable accuracy floor for any single- or twin-spout 25 kg open-mouth system that has been commissioned correctly [S1]. Twin-spout systems do not get a free accuracy upgrade; they share the same load cells and controller, just with two weigh hoppers running in parallel.
Selection Criteria: When Single Beats Twin, and When Twin Pays
Single-spout is the right answer when target throughput is below 600 bags/hour, when bag size or product changes more than once per shift, or when the bag-placer cannot reliably handle two streams of 25 kg bags without jam risk [S3][S5]. Twin-spout pays off when the line runs above 900 bags/hour for 8+ hours per day on a stable granule or powder, and the bag-placer has the pickup rate to feed both spouts [S4]. The PAYPER 1,800 bags/hour figure and the OMP-2090 B 900 bags/hour figure bracket the realistic 25 kg twin-spout envelope; anything in between is a matter of feeder design, not architecture [S2][S4].
The decision table below lines the main options up against the criteria that actually drive the spec for 25 kg open-mouth bagging:
1) Manual bag placer, single-spout net-weigh: 300-600 bags/hour, lowest capex, highest labor, suits sub-200,000 bags/year. 2) Automatic bag placer, single-spout net-weigh: 600-1,080 bags/hour, mid capex, one operator per 2-3 lines, suits 200,000-800,000 bags/year. 3) Automatic bag placer, twin-spout net-weigh: 1,000-1,800 bags/hour, higher capex, one operator per line, suits 800,000+ bags/year on stable granules or powders. 4) Semi-automatic gross-weigh single-spout: 200-400 bags/hour, lower accuracy (±100-200 g at 25 kg), suits low-cost woven PP bag programs where bag cost dominates [S1][S2][S3][S4].
Product Fit and Bag-Closure Constraints
Free-flowing granules (grain, seed, fertilizer prills, plastic pellets, sugar, salt) are the easy case for both single- and twin-spout 25 kg open-mouth, and the published 1,800 bags/hour twin-spout ceiling is realistically reachable only on this product class [S1][S3][S4]. Fine powders (flour, cement, fine minerals) cap out around 900 bags/hour even on twin-spout, because dust extraction, screw-feeder cut-off accuracy, and bag-settling time become the serial bottleneck before the second spout adds value [S2][S3].
Bag-closure choice interacts with throughput: plain sew (single or double stitch) is the standard on OMP-B lines and most PAYPER configurations, and is compatible with both single and twin spouts at full rated speed [S2]. Heat-seal or ultrasonic closure for PE and laminated woven PP bags can drop 25 kg throughput by 10-20% versus sewing, because the seal-and-cool dwell is longer than the stitch cycle, and this penalty is independent of spout count [S2]. Bag magazine capacity (480 bags on the OMP-B, similar on PAYPER) is the other hidden constraint: at 1,800 bags/hour, a 480-bag magazine needs a reload every 16 minutes, so magazine size and refill logistics should be on the same line of the spec sheet as bags/hour [S2][S4].
Integration and Footprint Reality
The OMP-B twin-spout line ships with a footprint of 4,230 mm L x 6,440 mm W x 5,240 mm H, and the single-spout configuration is roughly 60-70% of that floor area, which is the realistic ratio to expect across vendors for 25 kg open-mouth bagging [S2]. Electrical supply is standardized at 3 x 400 V (±10%) at 50 Hz or 3 x 440 V at 60 Hz, and ambient rating is 5-50 °C (40-122 °F), so a twin-spout line does not require any special utility upgrade over a single-spout line on the same plant [S2].
Dust collection is the one integration item that scales with spout count: a twin-spout flour or fine-powder line typically needs a centralized dust port sized for 1.5-2x the single-spout airflow, and EWINALL, PAYPER, and Premier Tech all flag dust extraction as a line-design item, not a bagger option [S2][S3]. For a 25 kg open-mouth bagging cell, plan the bag-placer pick rate, dust collection capacity, and bag magazine size before locking the spout count; the bags-per-hour number on the data sheet is a component rating, not a line rating [S3][S4]. For a deeper look at how throughput architecture decisions play out on the materials-handling side, the VLM throughput comparison covers a similar single-vs-dual decision in a different domain.