HOF Prüfsysteme

Trust in knowledge and experience

HOF Prüfsysteme GmbH is a company belonging to the HOF Enterprise Group. With its more than 30 years of experience, the company is the leading specialist in the manufacture of specialized leak detection systems for the automobile, aerospace, refrigeration, and electronics industries.

Highly motivated and qualified professionals work at the company location near Marburg in Lohra. A flexible service team stays in close contact with our clients both nationally and internationally, taking care of the needs of HOF system users.

Ensure future success

In the industrial environment, quality and reliability are parameters that determine the success of a company. HOF guarantees the quality and reliability of its leak detection systems for good reason. The company’s systems technology is developed with a strong orientation towards the demands of the future.

The highest quality every step of the way

...has set the company, which specializes in customized solutions, apart from the rest since its inception. From conceptualization to well-developed planning all the way through to conscientious production of a unit that is customized and impresses with its reliability. HOF testing systems are always a great investment in the future.

The specialist for leak detection with first-class problem solvers

Knowledge can only be of use if it is alive - in the minds of people. As a technological pioneer, HOF draws upon a large pool of specialists who know exactly what demands need to be fulfilled by the industry in the future. The high professional competence of our specialists is constantly deepened and expanded through internal and external training and further education. This way the competence necessary to consistently conceptualize, plan, and realize equipment specific to each client to the client’s fullest satisfaction is constantly expanded.

A team of responsible specialists

At HOF, a single team will always take full responsibility for the entire equipment system, not just for
individual parts of it. Every piece of equipment will be taken care of by a team of experts with specific project
knowledge that will also accompany the start-up, test runs, calibration, qualification, and validation. This way,
HOF clients enjoy the advantage of always having the same point of contact.

The best solution often calls for a completely new approach

The core of HOF’s company strategy is also the foundation for staying on the cutting edge in leak detection systems. HOF is dedicated to the early identification of new demands and the development of solutions in the form of groundbreaking new products.

Specialists as sought-after partners for industry

The efficiency of HOF systems, the service, and the adherence to deadlines are solid characteristics of HOF that are widely recognized by many companies. In addition to relying on our own experience and innovative capacity, close contact and collaboration with notable companies are also important to us.

Accompanying Practical Advising

HOF’s specialists have worked with industrial companies for many years and provide advice in many different areas:

  • Automation and software
  • Qualification
  • Process Technology and Development
  • Mechanics and Layout
  • Electro-technology

Experienced professionals accompany HOF clients with their solid specialized knowledge from conception all the way through to implementation in the production facility. It doesn’t matter if it is new construction, an expansion of existing equipment, or a modification.

Continuity and innovative capacity

HOF is the national and international leader in many new developments concerning the area of leak detection systems and will continue to lead in the future. Innovative specialized solutions, the flexible recovery of helium, the regulation of concentrations in filling circuits, and the localization of the leak on the object for quality assurance are examples of innovative capacity and the willingness of the company to find new ways of doing things. 

Competence in the search for the best solutions

HOF has worked on quite a few projects with international industrial companies to develop special applications. Always with the established goal of finding the best system solutions. This is another reason that HOF testing systems tend to always be up-to-date on the latest technology.

During this process, knowledge is collected to an extent not seen in this form anywhere else. Keeping this knowledge up-to-date and sharing it with others is part of the daily routine at HOF. Because knowledge can only be of use if it is alive – in the minds of people.

One point of contact and direct solutions – that is HOF

Successful project management can be measured quite simply: agreed services, deadlines, and costs are all adhered to. When it comes to project management, HOF believes in flat hierarchies, well-defined responsibilities, and a central point of contact who keeps track of every “thread” of the project. Our clients have long valued this method.

For every new project, our client will first have direct contact with our sales staff. Once a contract has been concluded the project manager takes charge, becoming the main point of contact for the client and taking care of the project until its successful completion and beyond. Internally the project manager will coordinate the tasks and requirements for the various departments within the HOF company for the duration of the project.

HOF project management organization chart

We let knowledge grow

Knowledge and know-how are important reasons for our success. As a technological pioneer, HOF draws upon a large pool of specialists who know exactly what demands need to be fulfilled by the industry. Their high professional competence is constantly supplemented and deepened through internal and external education and training.

HOF’s working processes are certified in accordance with DIN EN ISO 9001:2015.

Develop innovations, test innovations

Finding answers for the demands of tomorrow in the form of technological solutions is what drives us. To do this we work closely with our suppliers. Current topics include conserving resources by reducing the amount of testing gases used and by implementing dry running vacuum pumps.

Competence in Process Development

Qualified process development is also one of the services provided by HOF. This provides security, reduces processing times, and ensures that the quality of our products sets them apart from the rest.

Highest Standards for Development

Whether something new can be judged to be truly good depends on the quality of the test. Our work for industrial companies requires us to hold our developments to the highest standards. Extensive long-term tests are therefore an inextricable part of our daily work in the development department.

To the point: engineering

HOF develops practical groundbreaking solutions. Original, patent-ready solutions reflect the innovative capacity of the company. The highly qualified professionals at HOF do valuable work that gives HOF clients a clear advantage. Intense dialog with industry partners allow even technically challenging visions to become reality.

Mechanical Construction

HOF will take charge of all planning from the first design and concept studies to the drafting of an installment/layout plan all the way to manufacture drawings of individual pieces. All work is done by HOF in-house to ensure that deadlines are met and the best quality is provided.

Automation and software

Valid software is one of the most important requirements for the manufacture of leak detection systems. HOF is there every step of the way for the development and creation of software. Our own software specialists will accompany it from the design phase through to project planning, start-up, qualification, and service.

It all ends with a solution that is as standardized as possible while also fulfilling all your unique software needs.

Electrical hardware

HOF employees create complete circuitry documentation for projects including circuit diagrams, cable diagrams, parts lists, terminal diagrams, and many others. HOF has got everything taken care of from planning all the way to start-up:

  • switchboard layout,
  • assembly planning,
  • wear resistance,
  • safety engineering, or energy optimization

and the component selection goes along with it.

Everything under one roof: manufacturing

Manufacturing at HOF is comprised of the areas of metalworking, service, and electronics as well as measuring and control technology. Electrical, mechanical, installation work and customized manufacturing work are carried out in these areas by our very own workers. Construction of the switchboard is as much a part of the process as the wiring and complete functional testing of the equipment accompanied by the corresponding documentation. HOF has got everything taken care of from planning all the way to start-up.

Overview of manufacturing steps

  • Manufacture of high-quality components
  • Pre-assembly
  • Electrical engineering
  • Final assembly

Construction of a leak detection system for the automobile industry


Example of a cooling component

Final assembly of linear testing & filling equipment


Quality Assurance and Quality Standards

We have high expectations for our work, which is an important prerequisite for HOF’s success. The company’s processes are certified in accordance with DIN EN ISO 9001: 2008. Country-specific standards and policies such as the specified standards according to UL (USA) are adhered to. This ensures the quality of development and manufacture for equipment and systems.

Continual Quality Control

Additionally, all areas are subject to continuous quality control – from the receipt of goods to the different phases of manufacture all the way to completion. Supplier audits and documented start-up tests ensure that products always meet our high standards for quality.

Individual solutions made from high-quality components

The HOF company manufactures a wide range of client-specific analysis and testing systems – from simple applications with or without handling systems, all the way to industrial leak detection equipment with automatic transfer stations. High-quality industrial components and analysis systems such as vacuum pump assemblies, programmable logic controllers, or mass spectrometers are implemented in order to minimize downtime and reduce costs.

HOF Prüfsysteme Products

  • Test chamber equipment with automatic and manual loading
  • Sniffer equipment with various test media
  • Leak Detection Systems with Water Bath
  • Test Gas Recovery and Preparation Systems
  • Reconfiguration of Facilities and Modernization
  • Automation/Visualization Technology
  • Process Development and Optimization

HOF services

  • Advising and Support in Application
  • Complete Assembly
  • IQ-Installation Qualification
  • Calibration
  • OQ-Equipment Qualification
  • PQ-Assistance with Process Qualification
  • RQ-Requalification Measures
  • Maintenance and Servicing
  • Repair and modification of existing equipment with appropriate documentation





Customized leak testing

HOF relies on proven measurement procedures and methods for full product and process integrity. The conception and construction of fully and partially automated equipment systems are developed individually depending on the testing task as well as the production conditions and equipment surroundings.

Customized and innovative equipment systems can therefore be integrated into the respective production lines and can be adapted to individual production timing. Equipment availability and capacities as well as other parameters are specifically customized.

Start-up of a leak detection system

Fully-automated plant systems

...from HOF load the testing unit with the test subjects automatically and reliably take charge of filling the subjects with various test media. Filling pressure can be individually chosen as can further processing steps or test processes such as bursting strength testing, dimensional stability testing, welding, cutting, or flagging.

Documentation and archiving of measuring data are of course included. The software for PC and PLC regulation for controlling, parameterization, error notification, and remote control are individually adapted to the respective requirements. A monitor and panel PC allow for quick, understandable process visualization.

Semi-automated plant systems

...from HOF enable the manual loading and unloading of test objects. During this process, sealing tools must also be operated by hand. When using partially automated equipment systems with visually guided measuring units, further manual interventions in the operation of the process flow are also possible.

Radio frequency welding for redundant sealing

Special handling systems for optimized processing times

One provider for all testing methods

HOF leak detection systems are matched exclusively to the requirements of each client. In the process, HOF engineers always use the individual product as the starting point to develop exactly the right system. It is for this very reason that HOF leak detection systems can test various products for their airtightness – from heat detectors all the way to gearboxes.

Water bath tests

The test subject is sealed and exposed to pressure. In water reservoirs, a leak can be detected and localized by testers using the ascending bubbles.

Test gas sniffing method with the mass spectrometer

The probe of the test gas sniffer will search the object filled with test gas for any gas discharge.

Mass Spectrometer - Integral - Industry (test gas)

The test subject is filled in the vacuum testing chamber with the surrounding test gas. The mass spectrometer determines if there is a leak by comparing the leakage-air spectrum with a reference spectrum.

Dichtheitsprüfung mit Luft

Fall in Pressure Measuring Procedure

The sealed test subject is exposed to pressure and the lost pressure recorded.


Differential Pressure Measuring Procedure

Captures any possible difference in pressure in the test subject and in the reference object after the addition of pressure


Flow Behavior Process

The filling pressure in a sealed and filled test subject is stabilized. The measuring system attached to the test subject captures the fall in pressure.


Linear Testing and Filling Equipment

...from HOF ensure that automatic or manual loading can occur immediately after leak testing. The test subject will be evacuated after the test and – after the test gas has been extracted – filled with the desired fill medium. Different filling pressures can be individually set for this and the filling medium can be changed for individual test subjects simply by pushing a button.

Double testing for defect-free products

Test subjects that are identified as defective during the leak test will not be filled. The same applies for test subjects that do not meet further established quality criteria. Further processing will be discontinued at this point and the test subject will either be manually or automatically removed and marked accordingly. The test subject will only be filled and processed further if it passes both tests.

HOF ensures that the linear testing and filling equipment fits seamlessly into the respective production process. This also applies to further processing such as for closing, pinch-off, and electric resistance welding. These solutions from HOF are implemented in areas such as in the heating industry, climate control technology, and many other areas.

Heat detectors are separated
and welded in later processing steps.


Compact Construction of
Portable Test Stand

Our service for you

With HOF, your equipment will be worked on exclusively by our own professionals – even long after the equipment has left our facilities. HOF professionals will transport your system, construct it, get it started up, and qualify it too. This way redundancy is minimized and problems are non-existent.

In case of an emergency, you will always be able to reach one of our professionals at the telephone number +49 (0) 6462 9169-0. 24 hours a day, 365 days a year. Why? Simply because we know that our equipment is important for the production process and downtime must be kept to a minimum. In order to accomplish this, we have an emergency team experienced in servicing and manufacturing that knows your equipment right down to the last detail and can help immediately.

24 hours – seven days a week

Providing comprehensive service is important to us. For this reason, we won’t just hand off your equipment to someone else. We will transport your system, assemble it, get it in working order, and even qualify it. This way redundancy is minimized and problems are eliminated. HOF equipment is an important component of industrial production processes. That’s why our workers can be reached 24 hours a day and are ready to help immediately in case of an emergency.

Ready to handle an emergency 24 hours a day

At our core: Spare parts warehouse

Our in-house warehouse of more than 60,000 items ensures that essential spare parts are always readily available for all equipment in order to minimize downtime as much as possible.

Our emergency service at +49 (0) 6462 6080 can assist you right away.

Servicing and Remote Diagnosis

Idle machines can cause costly production delays. Regular servicing is indispensable in order to ensure that your equipment is running smoothly. Equipment servicing by HOF includes documented trial runs as well as remote diagnosis. This allows for the execution of diagnoses, repairs and the regulation of equipment systems. That way downtime is minimized and costs considerably reduced.

By the way: The HOF team is available to help with all brands of leak detection systems!

Individual Design and Concept Studies

A coherent concept is always the basis for the success of a project. As a specialist for individual solutions, HOF makes sure that leak detection equipment and systems are integrated as best as possible into industry and research.

Customized and functional

The basis for this is customized concept studies and strategies in 2-D and 3-D that take into account functional aspects as well as other important parameters:

  • Dependability of the equipment
  • Easy access for servicing and maintenance
  • Safety
  • Investment and availability of systems
  • Equipment capacities

Formulation of Customized Concept Studies

Imparting Knowledge

Training offered by HOF emphasizes conveying knowledge in an intense and personal way that is oriented towards operational practice. To be able to share knowledge in a goal-orientated way, HOF offers training courses matched to the corresponding interest group.

Practical Training

If you are interested in HOF training courses, please send us an email (info@hof-pruefsysteme.de) or call us at +49 (0) 6462 9169-0.

Any questions?