Dahlmann increases the number of representations of major German companies and during this period it also establishes a branch in the Dutch East Indies.

The bombing of Rotterdam city center on 14 May 1940 also destroyed Dahlmann`s office. Almost all administration is lost. After the war, Dahlmann returned to Rotterdam to continue the business.

The new start after the war is difficult, because the German industry has seriously suffered and production rates remain low. This situation is improved by the Marshall Aid and the Industries are depending on good representations abroad. Dahlman benefits from this, a new era is born. However, in the 1970’s, with the oil crisis and a global malaise, sales dropped. A new owner and director decides to expand. It is during this period that the important switch takes place from mainly operates as an agency to a designer of high-quality filtering techniques. The company splits its activities into three product groups: industrial technology, filtration technology and metallurgical products. Dahlman manages to close orders for large installations at Hoogovens, for DSM, Shell, Stork and food company DMV. Due to the growth of the company, the company moves to a business park next to Rotterdam Airport. During this period Dahlman is more likely to design and manufacture special products for customers. Manufacturing work that is usually outsourced is in a little while taken in hand with the acquisition in 1985 of construction works and pressure vessel builder Plate and Construction Works B.V. (Platex) located in Maassluis. This is how Dahlman`s relationship with Maassluis begins.

Dahlman in Maassluis

When Dahlman acquires Platex in 1985, the continues its operations in Maassluis. In 1986, a completely new building and fabrication facility was taken into operation. Dahlman continues to work on the expansion of the company in the new accommodation, and especially puts focus on the development of filter technology. In 1993 a new branch is opened in Geleen from where it operates frame agreements for the supply of filtration spare parts. In 1995, the company built a new office and production facility, there are now around 90 employees working for the company. Dahlman opened due to increased export activities branches in Malaysia and Bahrain.

Dahlman becomes “Royal”

On November 8, 2011, Queen Beatrix awarded the designation "Royal" to Dahlman. To be awarded the "Royal" designation, a company must meet certain conditions. The company must be at least 100 years old and occupy a leading position in its field. The company should preferably have an international appearance and flawless business operations. The company, board members and supervisory directors must be well-known and of undisputed behavior. The company received the award from the Commissioner of the Queen in South Holland J. Franssen, in the presence of mayor J.A. Karssen.

Royal Dahlman is developing further in a niche market and grows its reputation and number of qualifications in the industries. In 2015 the company decides to stop its manufacturing of construction works and pressure vessels as the international business forces suppliers to subcontract that work to specialist approved suppliers. This decision paves the way for implementing a new strategy enabling Royal Dahlman to focus even more on the development of filtration technology for high end applications in a niche market.

Royal Dahlman is acquired by Porvair plc.

In 2019 the company has been acquired by Porvair plc. Based in the Netherlands, Royal Dahlman supplies filtration services and technology to customers worldwide, with particular expertise in refining and petrochemical filtration engineering. Our two divisions, Dahlman Filter Technologies (DFT) and Dahlman Filter Services (DFS), each with a distinct offering in the filtration market, continue to operate within the current structure.

Royal Dahlman BV Downloads

Model MCB - Slurry Oil Filter Brochure