Derwent James Ltd

Dopak sampling systems exclusive UK representatives.

Derwent James Ltd were established in 2009 by Neil Finney as the exclusive UK representatives for Dovianus BV the Netherlands based manufacturer of Dopak closed vent sampling systems. Since then Derwent James Ltd have agreed additional partnerships with leading manufacturers of chemical process safety equipment.

Chemical hoses

We are UK representatives for Elaflex who are a German manufacturer of engineered hose assemblies & hose couplings extensively used in the petroleum industry with applications and installations in many other industry sectors worldwide, complementing this is a Swedish manufacturer of dry break hose couplings.

Pressure regulating & control valves

Additionally we represent a UK based specialist manufacturer of pressure regulating and control valves with experience in many sectors supplying very high accuracy regulating valves.

Mechanical interlocks and lockout tagout safety equipment

Finally we represent a supplier of mechanical valve interlocks and lockout tagout safety equipment. We are able to arrange both equipment supply and expert advice on lockout tagout procedures form yoru factory or installation.

Chemical process safety equipment is our area of speciality and we can call on the vast knowledge and experience of our partner companies to ensure the product you select is the right product for your application.

2016 is an exciting time for us at Derwent James with a great team of partner companies supplying chemical process safety equipment, all keen to further develop long term relationships with key businesses in the process industry in the UK and worldwide so follow us on Linkedin, Facebook and Twitter for updates.

Your interest in Derwent James Ltd chemical process safety equipment is important to us so do get in touch and if you feel we can help then we will be happy to discuss your application in more detail. Finally some references from our satisfied customers;

I worked with Neil for the supply of sampling systems from Dopak. I highly appreciated his competence, professionalism and courtesy” – Associate consultant

Neil provided excellent support during a number of projects. Neil helped the project team select, supply, install and successfully commission a number of new sample systems”. – Process Engineering Senior Manager

Neil worked well with me to fully understand my needs as a customer and develop a solution which worked right first time”. – Plant Process Engineer

Neil provided us with a first class service. He got us the information we required, went out of his way to increase our knowledge of the systems and gave us confidence”. – Piping Materials Engineer

I have no hesitation in recommending Neil whose knowledge of sampling systems enabled a number of projects to be completed ahead of time and well within budget”. – Senior Project Manager

If you have any questions or need more information then do get in touch:



Chemical sampling systems

Derwent James Ltd are the exclusive UK agent for Dopak sampling systems. Dopak are suppliers of hazardous chemical sampling systems.  Dopak sampling systems for hazardous chemicals improve safety and reduce spills. Dopak systems are easy to install. Dopak systems are simple to maintain.

Dopak sampling systems for hazardous chemicals are installed worldwide in all sectors of the process industry.  You can install a Dopak system to a pipeline or to a tank. With a Dopak sampling system you can take a hazardous sample safely and cleanly with no spills.

There are many types of Dopak sampling systems available. All systems are tailored to your site needs.

Hazardous chemical sampling systems – typical applications

  • Low pressure hazardous liquid
  • High pressure hazardous liquid
  • Fixed volume sampling
  • Viscous liquid sampling
  • Inline sampling
  • Top of tank sampling
  • Gas sampling

How to select the correct sampling system

We can quickly help you select the correct sampling system.  Give us a call or let us know a little about your application by email.  The type of information we will need is below;

  • What is the name of the media you are sampling?
  • Is it a liquid or a gas?
  • Are you sampling from a pipeline or a tank?
  • What type of connection do you have?
  • What is the pressure?
  • What is the temperature?
  • How much sample do you need?

You could also visit the NEW Dopak sampling systems website Here you can download lots of useful information about Dopak sampling systems for hazardous chemicals.  You can download brochures and datasheets.  There is also a digital presentation of all the systems showing each stage of their operation.

Dopak sampling systems - product selector

The Dopak produict selection tool is a brilliant way for you to see all Dopak sampling systems in action before you buy.  The online videos show each system in each stage of operation enabling you to see how it suits your particular application.  Take a look by visiting


Chemical sampling systems

Chemical resistant hoses

Our chemical resistant hoses are lightweight, flexible and reliable.  Our hoses can be used with many different hose couplings or fittings to give you a complete hose assembly for quick installation in your factory.  All our hoses are made by experts in our German factory.

Chemical resistant hoses – lightweight and flexible

Our hoses are high quality German manufactured and are safe to use.  Elaflex hoses are both flexible and lightweight and have a very long service life. Elaflex chemical resistant hoses can be used up to 16 bar pressure and comply with the EN standard 12115.  Our chemical resistant hoses are suitable for the majority of chemical transfer applications where safety and chemical resistance are important.

Chemical resistant hoses – dry break couplings

Using our chemical resistant hoses with our hose couplings or dry disconnect couplings gives a safe, clean and spill free solution to hazardous chemical transfers. Our dry disconnect couplings are easy to handle so will save you time, they are safe and they are environmentally friendly.  But above all they are reliable.

Pharmaceutical hoses

Hoses for pharmaceutical applications are also available as standard.  The new Elaflex hose ‘Elapharm’ is accepted for installation in pharmaceutical, food and biotech installations.  Elapharm meets prEN 16820.  Elapharm is super smooth making it an ideal hose for safe transfer of many liquids, powders and even crystals.

Chemical compatibility charts

You can check which of our hoses is best suited for your application by using our Chemical resistance charts at  then, just get in touch and ask us for a quotation or more details.

Chemical resistant hoses

Pressure regulating valves

Our pressure regulating valves, control valves and pressure relief valves designed and manufactured in the UK.  Suitable for gas or liquid applications up to 690 bar pressure. Our valves provide accurate control for your gas or liquid application whether it requires upstream or downstream control.

Pneumatic dome loading pressure regulating valves, zero leakage isolation valves, non return valves and emergency shutdown (ESD) valves complete our scope of supply. Our comprehensive choice of performance, configuration and material options will satisfy the most demanding and arduous applications.

Pressure regulating valves – UK manufactured

Manufacture of all critical components, final assembly and testing of each individual valve is carried out at our in-house factory in Loughborough UK which is part of the JRE Precision organisation. Our pressure regulating valves experts are able to readily provide individual solutions for both your special applications and a fast turnaround of standard valves.

Pressure regulating valves and stop valves

Not only do we offer pressure regulating valves, we are also able to offer a range of stop valves for high pressure applications.  The Presreg Series 404 offers a range of high pressure fully balanced stop valves with a 3/4″ nominal bore.  The series 404 stop valve range provides ultimate shut off control for many liquid and gas application.  This oxygen service valve is available in port sizes from 3/4″ up to 1 1/4″ with both male and female connection options Series 404 is suitable for oxygen, hydrogen ethylene and CO2.

Pressure regulating valves – tested and certified

All our valves are individually tested and certified in our approved facilities.  Our procedures suitable for cleaning oxygen and high purity equipment. Our team of experts are ready for your enquiry.  Contact us today with your valve specification or send us details of your current valve and we will be happy to provide a competitive alternative proposal by return.

Our pressure regulating valves range includes;

  • High pressure upstream regulators
  • High pressure downstream regulators
  • High flow regulators
  • Electronic signal controlled pressure regulators
  • Pneumatic dome loading regulators
  • Pressure relief valves
  • High pressure zero leakage isolation valves
  • Pilot operated isolation and ESD valves
  • System protection and fail safe valves
  • Automatic change over valves
  • Pipeline filtration
  • Bespoke valves and system design and manufacture

You can find further details on the full range of Presreg regulating valves at and  also at


Pressure regulating valves

Mechanical valve interlocks

Our mechanical valve interlocks safely lock all sizes and types of installed valves. Standard interlocks are available for retrofitting to your existing valves. Our interlocks also available for locking vessel enclosures, control panels and machinery access gates.

If your process has valves installed which are critical to the safety of the process then maintaining the integrity of these valves is vital.  Be sure the valve is not operated incorrectly or by unauthorized staff by using a mechanical valve interlock, this can prevent system failures or system leaks. A key operated interlock ensures the valve is only operated when it should be and by who it should be.  Valve operation is controlled when a key interlock is used.

Contact us to start the process of specifying your mechanical valve interlocks solution either with your contact details so one of our specialists can contact you or with specific mechanical valve interlocks application details for us to prepare a proposal.

The following information will help in the specification process but an example of what we can offer is shown here on one of our partner sites. 

For mechanical valve interlocks, we need to know:

  • The quantity of valves that need to be interlocked
  • The valve Type: for example is it a ball valve or a gate valve
  • What is the size of the valve? for example is the valve  2” 6” or 8”

For machine guarding interlocks, we need to know:

  • What is the isolating switch specification
  • What is the number of Access Gates/Guards
  • What is the type of access guards: e.g. fully body access, partial body access.

To start the process of specifying your mechanical valve interlocks contact us today describing the interlock application.  This can be a few words or a sketch of your installation.  Alternatively we can arrange for one of our interlock experts to visit your site and make a full assessment of your installation.

Mechanical valve interlocks

Lockout tagout equipment

Our lockout tagout equipment for the safe isolation of your plant machinery.

Our range of lockout tagout equipment is extensive. Many products are available on short delivery lead times and are competitively priced.  Ensuring the safety of your maintenance personnel is obviously vitally important so a good starting place is to use our extensive range of lockout tagout equipment.  The range includes padlocks, safety lockout hasps, electrical lockout products, group lockout boxes, electrical cable lockout, lockout accessories, car seals, gas cylinder lockouts, key and padlock cabinets, small lockout tags, lockout nags and kits, complete lockout stations,, safety padlock boards, electrical plug and socket lockout products, pneumatic lockout solutions, lockout signs and tags and all kinds of mechanical valve lockout products. The full scope can be seen here on our partner site Lockout products

Lockout tagout – car seals

Car seals are simple devices for locking valves in either the OPEN or CLOSED positions and are ideal for long term use. Our car seals are available ex-stock, are low price and are an effective isolation solution.  Once sealed the only way to remove a car seal is by cutting the cable.  We can send you a sample on request.

Lockout tagout – extensive range of products

The range of lockout tagout equipment available is extensive so do contact us with details of your application and we will reply quickly with a recommendation, our lockout tagout equipment includes;

  • Lockout Tagout procedures
  • Safety Padlocks
  • Multi lock hasps
  • Electrical Lockout
  • Lockout storage solutions
  • Group lockout and key management
  • Cable lockouts
  • Valve locks
  • Complete lockout kits
  • Tags and signs
  • Car-seals

Lockout tagout – contact details

For further information, prices and availability of any of our standard lockout tagout products or for specific  help and advice on your application get in touch via

Lockout tagout equipment

Acetic acid sampling system

Safe chemical sampling system are manufactured by Dopak sampling systems and supplied worldwide.  Dopak are represented exclusively in the UK by Derwent James Ltd.

Contact us today for a brochure or system datasheet and to discuss your sampling application.

You can read an introduction to our safe chemical sampling systems -by clicking the following link -


Derwent James Ltd Overview