A Guide to Selecting Weighing Bags: Analysis of Material Properties, Specifications, and Industry Applications

 

Weighing bags are packaging tools specifically designed for the accurate weighing of materials and are widely used in industries such as chemical, pharmaceutical, and food. Their core functions include providing safe material storage, convenient weighing operations, and efficient sealed transfer. This article will comprehensively analyze the characteristics of weighing bags from aspects such as materials, specifications, application scenarios, and selection key points to help users choose suitable products according to their actual needs.

 

I. Material Classification and Characteristics

The material of weighing bags directly affects their chemical resistance, temperature resistance, and scope of application. The common types include the following three:

1. PE (Polyethylene) Weighing Bags

PE material has excellent acid and alkali resistance and moisture - proof performance, as well as good flexibility, making it suitable for the weighing of most conventional materials. According to different densities, PE is divided into low - pressure high - density (HDPE) and high - pressure low - density (LDPE). Among them, HDPE bags are more durable, while LDPE bags have stronger flexibility. In addition, PE bags have a wide thickness range (0.008 - 0.2 mm), and users can choose different specifications from 10 to 200 microns according to the load - bearing requirements.

2. PP (Polypropylene) Weighing Bags

PP material can withstand high temperatures (up to over 120°C) and has high mechanical strength, making it suitable for scenarios that require high - temperature sterilization or operations in high - temperature environments. Its transparency is slightly lower than that of PE bags, but it has better tear resistance and is suitable for packaging granular or powdery materials.

3. PVC (Polyvinyl Chloride) Weighing Bags

PVC bags have excellent transparency, which facilitates the observation of the material status inside the bag. At the same time, they have moisture - proof and corrosion - resistant properties. However, PVC has poor low - temperature resistance (the minimum applicable temperature is about - 20°C), and incineration may release harmful gases, so attention should be paid to environmental protection treatment.

 

II. Core Specification Parameters

1. Volume Range

The capacity of weighing bags covers a wide range, from 0.25 kg to 40 L. Users can choose according to the volume of the materials. For example, small bags (10 cm × 15 cm) are suitable for micro - weighing in laboratories, while large bags (60 cm × 80 cm) can meet industrial batch requirements.

2. Open - Mouth Design

Most weighing bags adopt an open - mouth structure, which facilitates the pouring or taking of materials. Some bag types are equipped with self - sealing bone strips (such as ziplock bags), which can be opened and closed repeatedly to improve the sealing performance.

3. Sealing Methods

Common sealing methods include heat - sealing machine sealing, V - type bag clip fixing, and cable tie binding. Heat - sealing machines are suitable for scenarios that require aseptic transfer (such as the pharmaceutical industry), while cable ties are suitable for temporary packaging.

 

III. Industry Application Scenarios

1. Biopharmaceuticals

For the weighing of raw materials in the liquid - preparation stage, medical - grade PE bags with low endotoxin and gamma - irradiated sterilization should be selected to reduce the risk of contamination.

2. Chemical Industry

For corrosive powders or liquids, HDPE bags with strong chemical resistance are recommended; in high - temperature environments (such as feeding into a reaction kettle), PP materials should be given priority.

3. Food Industry

Food additives, seasonings, etc. need to meet food safety standards. It is recommended to choose colorless, odorless PE bags that have passed food - grade certification.

 

IV. Key Points for Selection

1. Matching of Thickness and Bearing Capacity

For lightweight materials (such as medicinal powders), thin bags with a thickness of less than 0.03 mm can be selected, while for heavy particles, thick bags with a thickness of more than 0.08 mm should be used to prevent breakage.

2. Transparency and Functional Requirements

Transparent bags facilitate the observation of the material status. Anti - static bags are suitable for packaging electronic components, and ultraviolet - shielding bags can protect photosensitive materials.

3. Environmental Protection and Compliance

Recyclable PE materials should be preferred, and PVC bags containing plasticizers should be avoided. When contacting food or drugs, it is necessary to confirm that the product has passed relevant safety certifications.

4. Sterilization Process

In medical - grade scenarios, pre - sterilized (such as gamma - irradiated) bags should be selected to reduce the subsequent cleaning and verification links and improve efficiency.