Exhaust Gas Cleaning and NOx Reduction: What Our Register Shows

Exhaust gas cleaning systems, NOx reduction technology and the monitoring equipment that goes with them are among the most heavily regulated equipment categories on board a modern vessel, and the number of certified products keeps changing as manufacturers add new models and retire old ones. For a technical superintendent comparing scrubber suppliers, or a buyer working out which NOx control systems actually carry a current approval, the practical question is rarely whether the technology exists. It is which specific products and manufacturers hold a valid, checkable approval right now.

This overview is built from three of our own datasets rather than from manufacturer marketing claims. The first is our type-approval register, filtered to the product types that cover exhaust gas cleaning, NOx reduction and emission monitoring equipment. The second is our equipment library, where a model is only counted once a datasheet has actually been checked against the manufacturer's own documentation. The third is our supplier directory, narrowed to firms whose profile mentions scrubber, exhaust gas or emission work. None of the three is a full picture of the global market on its own; together they show what is documented, certified and searchable through our own systems, with a data snapshot dated September 2026.

The intended reader is anyone who has to specify, buy, retrofit or service this equipment: technical managers at shipowners, procurement staff at management companies, yards planning a scrubber retrofit, and service firms trying to work out where the certified products and their manufacturers actually sit today. Every number below is quoted with its source, so it is always clear whether a figure comes from the type-approval register, the datasheet-checked equipment library, or the supplier directory.

What our register covers for exhaust gas cleaning and NOx reduction

In our type-approval register, entries whose product type matches exhaust gas cleaning, NOx reduction or emission monitoring total 532 products, held by 66 manufacturers. That is the full population this overview draws on for approval-level detail; everything in the sections on product types, manufacturers and validity below is a slice of these 532 entries.

The certificates split into two groups. Marine Equipment Directive certificates account for 486 of the 532 products in our register, and Type Approval certificates cover the remaining 46. In practice the Marine Equipment Directive group is dominated by the scrubber hardware itself, while the Type Approval group carries most of the NOx-specific and monitoring equipment, a pattern that becomes clearer in the breakdown by product type below.

Product types in the register

Our register groups these 532 products into six product types. The list below gives the number of approved products and the number of manufacturers holding at least one approval in each type:

• On board exhaust gas cleaning systems (Marine Equipment Directive) — 485 products from 37 manufacturers in our register; this is the scrubber hardware itself, in open-loop, closed-loop and hybrid configurations.
• Emission Monitoring System (Type Approval) — 18 products from 14 manufacturers in our register; continuous emission monitoring instrumentation used to demonstrate ongoing compliance.
• Exhaust gas cleaning systems for the reduction of NOx (Type Approval) — 15 products from 13 manufacturers in our register.
• NOx Selective Catalytic Reduction Control System (Type Approval) — 12 products from 9 manufacturers in our register; the control systems that run SCR after-treatment.
• NOx analyser permanently placed on board and for use on board as per NOx Technical Code 2008 (Marine Equipment Directive) — 1 product from 1 manufacturer in our register.
• SOx Exhaust Gas Cleaning Control System (Type Approval) — 1 product from 1 manufacturer in our register.

The pattern is clear: on board exhaust gas cleaning systems make up the large majority of everything in this part of our register, and every other category, monitoring, NOx-specific cleaning, SCR control and the two single-product categories, is comparatively small. A buyer researching scrubbers will find far more choice in our register than a buyer researching a standalone NOx exhaust gas cleaning system or an SCR control unit, simply because that is where most of the approved product population sits.

Who holds the approvals

Twelve manufacturers stand out with double-digit product counts in our register:

• Wartsila Moss AS, Norway — 95 products in our register.
• ME Production A/S, Denmark — 42 products in our register.
• Hyundai Heavy Industries Power Systems Co., Ltd., Republic of Korea — 38 products in our register.
• Ecospray Technologies S.r.l., Italy — 36 products in our register.
• ZHEJIANG ENERGY MARINE ENVIRONMENTAL TECHNOLOGY CO.,LTD, China — 32 products in our register.
• Panasia Co., Ltd., Republic of Korea — 30 products in our register.
• Alfa Laval Nijmegen B.V., Netherlands — 29 products in our register.
• Yara Marine Technologies AB, Sweden — 28 products in our register.
• Langh Tech Oy Ab, Finland — 20 products in our register.
• Value Maritime B.V., Netherlands — 16 products in our register.
• Cross Rip Ocean Engineering, LLC, United States of America — 13 products in our register.
• LAB S.A., France — 13 products in our register.

The top three names on that list, Wartsila Moss AS, ME Production A/S and Hyundai Heavy Industries Power Systems Co., Ltd., together hold roughly a third of all 532 products in our register, a meaningful concentration at the top even though the remaining approvals are spread across dozens of smaller manufacturers.

Manufacturer identity is not always tidy in the underlying certificate data. Looking at how the equipment library's manufacturer names map back into the register, entries recorded simply as Wartsila Moss AS account for 103 products under a single register name, while 13 further register entries recorded just as Wartsila add up to another 204 products. Alfa Laval Nijmegen B.V. carries 30 products under its own name, Alfa Laval Technologies AB carries 64, Wartsila Water Systems Ltd. carries 51, and 13 more entries recorded simply as Alfa Laval add up to 203 products. For due diligence, that means searching a single legal-entity name in the register can understate a manufacturer group's real approval count.

By number of manufacturers rather than number of products, our register's country breakdown looks a little different from the top-manufacturer list above. Germany leads with 12 manufacturers holding at least one approval in our register, followed by China with 11, the Republic of Korea with 7, Norway with 6, Sweden with 5, the United States of America and Finland with 4 each, and the Netherlands, Japan and Denmark with 3 each. Germany and China lead on breadth of manufacturers, while Norway's single strongest entry, Wartsila Moss AS, leads on approved product volume; breadth and concentration are two different questions, and our register answers them differently.

Validity and expiry

Of the 532 products in our register, 528 currently carry a valid certificate status and 6 are recorded as expired. That is a reassuringly small expired share, but it is not zero, and a certificate that shows as expired in our register is not something a buyer should specify against without checking first.

Looking ahead, our register also records scheduled expiry years for a subset of certificates: 10 are due to expire in 2026, 13 in 2027, 13 in 2028, 4 in 2029, 5 in 2030 and 2 in 2031. None of that is a reason to avoid a product outright, since most industrial certificates get renewed in the ordinary course of business, but it is a reason to ask for the current certificate rather than relying on a register snapshot, especially when a delivery or drydock date falls close to one of those expiry years.

For a procurement team, the practical takeaway is simple: treat register status as a starting point, not a substitute for asking the manufacturer or class society for a current certificate copy at the time of order, and check the stated expiry date against the vessel's own delivery or next drydock window before committing.

What the equipment library adds

Beyond the type-approval register, our equipment library carries a dedicated Exhaust Gas Cleaning category covering scrubber systems for SOx emission compliance under MARPOL Annex VI, with equipment types spanning SOx Scrubber, Open Loop Scrubber, Hybrid Scrubber, Closed Loop Scrubber, Exhaust Gas Cleaning System (Scrubber) and SCR / NOx Reduction System entries. Within that category, 133 models currently carry a datasheet we have verified against manufacturer documentation. None of those 133 models yet carry a fully verified set of key figures in our library, so a buyer should still request performance figures directly from the manufacturer rather than assume the library already holds engineering-grade specification data.

Six manufacturer names in the library carry at least one datasheet-backed model:

• Wartsila Moss AS — 92 datasheet-backed models in our library; example: V-SOx 20 MW EGC system installed onboard HUNTER IDUN.
• Alfa Laval Nijmegen B.V. — 30 datasheet-backed models; example: PureSOx 68 Single Inlet Sea Water System.
• Alfa Laval Technologies AB — 5 datasheet-backed models; example: Alfa Laval PureBilge OWS model 2515, 2505, 5015, 5005.
• Wartsila Water Systems Ltd. — 3 datasheet-backed models; example: OWS 500, OWS 1000, OWS 2500, SWC 2500R, OWS 5000, SWC 5000.
• Wartsila — 2 datasheet-backed models; example: Wartsila Open Loop Scrubber.
• Alfa Laval — 1 datasheet-backed model; example: PureSOx Open Loop.

Our library associates this equipment category with bulk carriers, container ships, general cargo vessels, tankers and oil tankers as the typical vessel types fitted with this kind of exhaust gas cleaning equipment.

The library's service records point to a recurring set of failure modes across this category: internal corrosion of the scrubber tower, pH sensor calibration drift, scale, corrosion or solids buildup that damages tower internals, piping or treatment equipment, pump seal failure, pump, blower or fan faults that cause low circulation or gas flow and trigger a system shutdown, seal, valve or piping leakage that causes liquid or gas leakage and unstable process pressure, general scrubber material corrosion, and wash water quality violations.

Service guidance recorded against this category is consistent with those failure patterns: continuous emission monitoring calibration is treated as mandatory rather than optional, wash water pH needs regular monitoring, open-loop operation is noted as restricted in some ports and waters while closed-loop operation needs NaOH consumption monitoring, and an annual internal inspection plus an annual scrubber survey aligned with class requirements are recommended across the category. Several notes also flag that open-loop-only systems are simple and comparatively low-cost but have restricted operability in emission control areas and in a number of ports, and recommend monthly pH sensor calibration together with wash water analysis in line with MEPC requirements and continuous emissions monitoring.

Where to find service and supply

Our supplier directory lists 315 firms whose profile mentions scrubber, exhaust gas or emission work. The country breakdown among these firms is led by the United Kingdom with 28, followed closely by the United States and Greece with 27 each, China with 24, Germany with 22, the Netherlands with 21, Norway with 20 and South Korea with 17, with the remainder spread across other countries.

A handful of examples from the directory illustrate the range of firms involved, from shipyards handling retrofits to manufacturers of the cleaning systems themselves:

• TK Tuzla Shipyard (ERKAL Nakliyat), Turkey — a ship repair yard in Tuzla focused on scrubber and ballast water treatment system retrofits alongside emergency repairs.
• GES SHIP - Global Engineering Service for Ship, Turkey — a technical ship agency in Istanbul offering supervision and scrubber installation support among other services.
• Weihai Puyi Marine Environmental Technology Co., Ltd., China — a manufacturer of open, closed and hybrid exhaust gas cleaning systems.
• Shanghai Bluesoul Environmental Technology Co., Ltd., China — a manufacturer of hybrid open and closed-loop exhaust gas cleaning systems.
• Bona Marine (Taizhou) Co., Ltd., China — a manufacturer of marine heat exchangers that also lists scrubber-related equipment alongside ballast water treatment systems.

How to use this when specifying or buying

Putting the register, the library and the directory together, a few concrete steps help when actually specifying or buying exhaust gas cleaning or NOx reduction equipment:

• Identify which of the six product types in our register actually matches the equipment being specified, a scrubber, a standalone NOx exhaust gas cleaning system, an SCR control system, or emission monitoring instrumentation, since approval numbers and manufacturer counts differ sharply between them.
• Search a manufacturer under every name variant that might apply; group entities can appear as several separate register names, as the Wartsila and Alfa Laval entries above show.
• Ask the manufacturer or class society for a current certificate copy rather than relying on a register snapshot, and confirm the status reads valid rather than expired.
• Check the certificate's expiry year against the vessel's delivery date or next drydock window, particularly for anything scheduled to expire in the near term.
• Where a datasheet-backed model exists in our equipment library, review its typical failure modes and service notes before finalizing a specification, so maintenance planning starts before installation rather than after the first failure.
• Use the supplier directory to find service and retrofit support close to the vessel's trading pattern or next yard period, filtering by country where relevant.
• Remember that a register count reflects certified, documented products only, not total market presence; a manufacturer with a short entry in our register may still be active well beyond what is captured here.

Frequently asked questions

How many exhaust gas cleaning and NOx reduction products are in the register?

Our type-approval register currently lists 532 products across the exhaust gas cleaning, NOx reduction and emission monitoring product types, held by 66 manufacturers in total.

Which certificate group covers most of these approvals?

Marine Equipment Directive certificates cover 486 of the 532 products in our register, largely the on board exhaust gas cleaning systems category. The remaining 46 fall under Type Approval, covering NOx-specific systems, SCR control and emission monitoring equipment.

Is the equipment library's model count the same as the register's manufacturer count?

No. The library counts 133 models with a datasheet verified against manufacturer documentation across six manufacturer names, a separate, smaller and independently checked figure from the 532 products and 66 manufacturers in the type-approval register. The two datasets should not be added together or treated as the same population.

How many of the register's certificates have already expired?

Six of the 532 products in our register currently show an expired status, against 528 recorded as valid, with further certificates scheduled to expire between 2026 and 2031. A buyer should always confirm current status directly rather than relying on either figure alone.

This article is provided for general information and education. It does not replace professional advice.