Fields of application for weighing scales in the fish industry and fish trade

Gravimetric determination of mass using weighing scales of different design is today indispensable in all areas of life, whether commercial, economic or personal. Weighing technology is used everywhere, for example to check catch volume, to register or trace the movement of goods, or to enable adherence to exact recipes as well as to promote honest trade. The range of available weighing scales is accordingly large and there is a solution for almost every application and measuring range.

Caviar weight is checked time and again for accuracy during the filling process by means of sample weighing of individual jars.

Before a fishmonger can name the price he places the fish fillet on the weighing scales. Individual ingredients for a planned dish are often weighed out on kitchen scales, and after a good meal weight-conscious consumers will get onto the bathroom scales themselves. But weighing takes place in many other areas, too. Most of us are indeed quite unaware of just how much modern life is based on weighing. Without these possibilities for accurate weight determination our existence would be inconceivable in its present form. Whether in freight traffic, import, export, buying or selling – nearly everything is precisely weighed to a gram or a tonne. Customs and taxation authorities use weighing scales, they are required in research laboratories, in medicine, at the chemist’s and in private households… No sector of the economy, no company, no commercial establishment can get by without weighing technology today. And so the range of available scales is accordingly large, from small pocket scales to multifunctional tabletop scales and huge standalone floor scales on which full containers and complete trucks can be weighed. Some of them are firmly installed, others are transportable, older models are perhaps analogue devices, but most of them are today digital. They are fast, precise, and can in addition be linked to computer technology.

During everyday use of scales it is mostly ignored that strictly speaking it is an object’s mass and not its weight that is determined by weighing. The right term would be weight-force since weight does not only depend on the object under observation but also on the force of gravity in the location of weight determination. Consequently an object at the top of a high mountain would have a slightly lower weight than it would down in the valley below. Its mass (measured in grams or kilograms) is, in contrast, independent of place, i.e. is the same everywhere. In everyday general use, however, the word “weight” is used, as it is in the commercial sector, too. On product labels, for example, there are often details on the fresh, raw or drained weight. From the point of view of physical definition that might not be quite correct but it is not unreasonable for in everyday life it is more the weight than the mass which corresponds to the matter we are dealing with. Apart from that, laws and regulations mostly refer to the weight and not the mass.

Hand packaging enables attractive positioning of the smoked salmon slices, and simultaneous weighing prevents over and underweight tray packs.


Industrial weighing scales have to meet robust requirements

Weighing is required frequently in industry, and often for very different purposes. Typical application fields are the documentation of incoming and outgoing goods, weight controls when mixing ingredients, quality and efficiency checks during ongoing production processes, or the monitoring of product pack weights. There are special designs of weighing scales for almost every field of application and they are optimally aligned to the respective purpose. Most of them are probably suited to various different weighing functions but some of them were developed for very special applications, for example, for moisture determination in raw materials and finished products, for dosage of certain ingredients, or to enable the achievement of predetermined target weights. Checkweighers are used to determine whether pack weights are within the permissible tolerances and show the results with a plus or minus sign, other scales count product pieces on the basis of their individual weights, or control dispensing and filling systems independently. A lot of scales can today do much more than simply measure weight. They are an integral part of the production lines and their potential application areas are becoming increasingly broad.

Regardless of the task or application area, the demands placed on industrial scales are generally very high. They have to function reliably under adverse conditions, have to cope with dirt, high humidity levels or difficult temperature conditions and yet still be fast and accurate. This also applies to scales used by companies working in the food industry, for example in the fish industry. Weighing scales in this sector are often exposed to ice, water and salt, they have contact with slime and scales from the fish, have to tolerate processing smoke, oil, vinegar and edible acids. For that reason alone scales that come under consideration for use in the fish industry mostly have to be very robust, and largely insensitive to dust and splash water. Not only the weighing process itself but also the transmission of measured data has to be guaranteed at all times. A lot of scales, among them simple industrial models, already have interfaces for feeding the measured data into a company’s computer network where they can be stored and used for tracing individual product batches, or for enabling capacity and efficiency controls in individual production sections. The software of most scales manufacturers in the meantime includes counting options that can add up individual weighing results over longer periods and networking the scales with the central computer then also facilitates sporadic checks in between or annual inventories. Precise measurement data that are readily available and accessible do not only save time and money but can also support decision-making at management level.

Some fishmongers like to use suspended scales that are particularly space-saving and hygienic at service counters.
Intermediate electronic weighing units and the automatic zeroing option make it possible to determine the fish’s net weight already at harvesting.


Automatic zeroing simplifies net weight measurement

The first time products have to be weighed in a company is usually upon entry of the raw materials. Where fish is concerned it is not only the cooling temperature during transport that has to be checked but also whether the quantity of delivered fish corresponds to that ordered. Different weighing scales are used here, depending on the size of the company and graduation of incoming goods from single cartons and pallets to containers. Firmly installed vehicle scales and weighing bridges that can weigh trucks complete with their freight are probably only rarely found in the seafood industry. When the need arises, however, there are transportable systems that can be set up quickly and provide precise measurement data. Another option for heavy or bulky loads can be weighing modules, weighing feet and load corners. These separate weighing elements are placed below the four corners of a crate or container and in interaction with one another display the weight.

For some weighing tasks, for example when harvesting fishes in aquaculture, cranes or suspended scales are a good solution. They are simply fixed to the crane rope above the net and then measure the weight of the fish contained in the net. The possibility of automatic zeroing is of advantage here and most electronic scales offer this today. It enables the setting of the weight of the net and other gear to zero so that only the fish weight is measured. This option is also very useful when measuring weight using floor scales that are mainly designed for weighing medium to heavy loads. These scales are among other things used for weight control of live fish, and speed is of particular importance here. To start with the fish farmer gets onto the scales himself with all his gear and the empty net and then sets the scale to zero. Every time he subsequently walks over the floor scales with a full net only the weight of the fish is recorded. Today such scales usually have a memory function for summing the individual weights so that their total weight is also immediately recorded. This makes it possible to control at any time how much fish has already been loaded or moved. Some scales can even be programmed so that upon exceeding a set critical weight limit an acoustic or visual signal will be given.

Pricing is based on weight at Asian markets, too, although the scales used there are mostly very simple constructions and rarely absolutely precise.


Integration of weight measurement in production processes

These and other additional functions can greatly enhance the efficiency of weighing systems. Whether they work in the milligram range or with heavy loads, modern industrial scales often offer helpful additional functions that facilitate accurate dosing, mixing or checking and can thus prevent individual measurement errors. Some manufacturers even advertise with the promise that their scales can be exactly tailored to the specific needs of their customers. If the design and construction allow, electronic weighing modules and cells can often be directly integrated into existing production lines, vehicles, lifting platforms or other neuralgic points within the workflow. Where pallets have to be weighed frequently upon arrival at the company or prior to dispatch, U-shaped pallet scales can be useful that are available in almost all dimensions for standardized Euro pallets, standard aircraft pallets, and even special designs of different size. As an alternative there are also mobile weighing systems that are directly integrated into the forks of the pallet- or fork lift truck. Such scales are available in numerous varieties for different weight ranges. They are particularly time and money saving because they do not only transport the goods but weigh them at the same time. If this solution is not attractive there are also drive-through flat-bed scales that usually have a built-in ramp. These scales do not have to be sunk into the floor but can simply be positioned on it. The flat construction with a ramp allows one to push rollable transport devices from wheelbarrows to carts manually without great exertion over the scales. These weighing scales also usually have an automatic zeroing option which makes it easier to weigh the pure net load.

Not only is there a great variety of designs and dimensions for scales but also of options for their installation and the materials of which they are made. They can be mobile or fixed to the floor, suspended or reclining constructions. For the food industry they are mostly made of hygienic stainless steel but they can also have galvanized zinc or robust plastic coatings.

Due to the huge variability of weighing systems it is today possible to integrate them into production processes wherever they are deemed necessary or seem useful. The fish industry, too, has need of weighing scales at various processing stages for sorting fillets and portions by weight, adding sauces and marinades in the right weight proportion, batching finished products to target weights, or marking self-service packs for retail sale according to weight. Such weight measurement is frequently carried out in continuous processes at a high speed but should still be accurate and reliable. However, powerful modern weighing systems meet these difficult requirements, too.


Electronic options considerably expand the use range of scales

Investments in complex and accordingly expensive weighing systems are particularly worthwhile for big companies with continuous production processes and high product throughputs. In contrast, in small artisanal businesses multifunctional scales are sooner found that are equally suited to different tasks and universal usage. As a rule these are transportable tabletop scales that can be used in very different production areas. They are usually marked by high accuracy and frequently offer numerous options that are normally sooner expected from big, complex (and accordingly expensive) systems. This means that users do not have to do without the possibilities of modern measuring electronics. Depending on the chosen version multifunctional tabletop scales are used, for example, for portioning and for control purposes, e.g. to monitor correct pack weights. A signal sounds when products are overweight or underweight and they can be automatically sorted out. Some scales models can also be linked to databases and used for marking the product prices. Particularly large scales manufacturers optionally offer suitable software packages that enable the user to design the labels on the computer himself and then print them using a suitable printer.

These scales have a display on the customer side that can show recipes, suitable wines or additional product information.

Additional flexibility is sometimes possible with special scales that have two or even more weighing and resolution ranges. A two-range device can for example weigh accurately to one gram up to 3 kilograms and in the second further reaching measurement range the weights will be displayed with slightly less accuracy. The combination of highly powerful weighing systems with the possibilities of modern electronics and filling, dosing, portioning stations today enables even their use within dynamic processes. A difficult usage area that poses huge logistical requirements. The flavour and quality of the finished product can depend on accurate dosing of individual components, underweight packed products would constitute deception of the consumer, overweight product packs a loss for the producer. When filling flowable / pourable products the target weight must be calculated in advance and the filling valve be closed when the last little bit of the necessary quantity is still falling into the product, so that is trickles onto the product after the valve has closed. By including the scales in electronic industrial terminals this demanding task can in the meantime be solved to everyone’s satisfaction. These weighing terminals thus not only calculate the weight of every individual pack but also guide the engines and valves of the dosing systems and register all production relevant data. Some terminals are even capable of learning and can record the specific flow behaviour of individual products and take this into account when opening and closing the valves. They are so to speak “self-optimizing” systems.


Weighing systems as complete solutions for the retail sector

Although more and more products arrive at the retailer’s ready weighed, ready packed and marked with price according to their weight, supermarkets and other retailers continue to be one of the most important user groups for scales. They are not only found at service counters but also as self-service and control scales for the customers or – hardly recognizable as scales – as integrated weighing modules at the checkout. All of these scales have special abilities that make them suited to their respective application field. Scales at service counters, for example, have to be easy and quick to clean in between times – hygiene and efficiency are key here. A lot of scales are fitted with a receipt or label printer and a computer unit that calculates the price and generates the product-specific barcode which can then be scanned for payment at the checkout. If however the product is to be paid for directly at the counter as is often the case on markets and at the fishmonger’s the scales can also be fitted with a cash drawer or function. The options for service counter cash desks are huge and they are available both in normal standing and in space-saving suspended versions that are often preferred particularly at fish retail counters. Manufacturers pay attention that their scales will not prevent eye contact between the sales assistant and the customer, for example.

Scales of mobile fishmongers at weekly markets have to meet special requirements because they are moved so often during transport.

Modern scales can even support communication at the sales counter for some of them are fitted with a computer display on the customer’s side that shows recipes, suitable wines and other information on the product. But even without screens the scales displays can be designed in various different ways. Vertical or flat, with a swivel arm or with displays on both sides that can be seen directly by both customer and the service staff. Because weighing technology and its periphery are today mostly modular certain elements can be arranged in the counter area so that the technology is largely “invisible”. This reduces potential soiling and hygiene risks of course, too. Depending on their design such weighing systems can be real complete solutions that take some of the work load off the retailer and support him in the numerous tasks he has to fulfil: weighing, calculating prices, taking the money, recording, printing, documenting, advising the customers, drawing attention to other products, informing. Some scales can even be accessed directly via the internet so that the maintenance technicians can repair the systems quickly in the case of disturbances or errors. A further option of modern weighing systems that helps save time, money and trouble.