Description
GPH843T5L UV lamp Oman — 40W 843mm 4-pin germicidal replacement bulb

The GPH843T5L UV lamp is the standard 40W germicidal tube used in mid-size ultraviolet water sterilizers across Oman, and UV Water Systems keeps it in stock in Muscat. It measures 843mm with a 4-pin single-ended T5 base, emits at 254 nm, and drops straight into AquaPro UV12-L chambers as well as equivalent 40W housings from Viqua/Sterilight, Pura, Polaris, Aqua Ultraviolet and Atlantic UV.
This is the workhorse lamp for 10 to 25 GPM systems — the size fitted to villa whole-house units, restaurant and café water lines, small hotel plant rooms and post-RO polishing on commercial machines. Because the same envelope is sold under a dozen different part numbers, buyers often overpay through the original equipment channel for a lamp that is dimensionally and electrically identical.
GPH843T5L UV lamp Oman — technical specifications
| Model / ANSI code | GPH843T5L (also listed as GPH843T5L/4, GPH843T5L/4P) |
| Power | 40 W |
| Arc / overall length | 843 mm (33.5 in) |
| Base | 4-pin single-ended, T5 / T5F |
| Lamp diameter | 15 mm (T5) |
| Type | Low-pressure mercury, hard glass |
| UV-C output at 100 hours | Approx. 14.5 W |
| Germicidal output | 254 nm UV-C |
| Rated service life | 9,000 operating hours (approx. 12 months continuous) |
| Supplied by | UV Water Systems — Uniqueness View LLC, Muscat, Oman |
GPH843T5L UV lamp Oman — compatibility and cross-references
- AquaPro UV12-L and AquaPro 12 GPM chambers
- Viqua / Sterilight S36RL equivalent — S12Q, S12Q-PA, S12Q-Gold, SSM-39, S24Q, S24Q-Gold, S40Q, SUV 24P–100P
- Pura UV20, UV40 series
- Polaris and Aqua Ultraviolet 40W chambers
- Atlantic Ultraviolet and Emperor Aquatics 40W housings
- Any 40W chamber taking an 843mm 4-pin lamp
Before ordering, measure the old lamp end to end and count the pins. Length and pin configuration determine fit — the printed part number on a failed lamp is often unreadable. If you are unsure, send us a photo and we will identify it.
Where the GPH843T5L UV lamp Oman is used
We supply this lamp to villa whole-house UV units in Al Khuwair, Al Hail and Mawaleh, to café and restaurant chains running post-RO UV on ice makers and coffee lines, to school and labour-accommodation drinking water systems, and to light industrial process water lines. In Oman’s conditions — high ambient temperature and hard groundwater — chamber water temperature stays well within this lamp’s operating band, but sleeve fouling is the main cause of lost disinfection performance, so lamp and sleeve should be serviced together.
When to replace your GPH843T5L UV lamp Oman
UV-C output decays long before the lamp stops lighting. A germicidal lamp still glowing at 15 months may be delivering well under the dose its chamber was sized for, which means the water leaving the system is no longer being disinfected to specification. Replace on hours, not on appearance. For systems running continuously, that means once every 12 months. Log the change date on the controller or on the chamber label so the next service is scheduled rather than remembered.
Handle the quartz sleeve at the same visit. Scale and iron deposits on the sleeve block UV-C just as effectively as a weak lamp, and in Oman’s high-hardness groundwater sleeves foul faster than most manufacturers’ generic guidance assumes. Clean the sleeve with a mild acid descaler, inspect the O-rings, and replace the sleeve outright every three to five years.
Standards and references
The UV dose a chamber must deliver, and the reasoning behind the annual lamp change, come from published drinking water guidance rather than from equipment marketing. The WHO Guidelines for Drinking-water Quality set out the microbiological targets disinfection is designed to meet, and the International Ultraviolet Association publishes the dose and validation practice the industry works to. We size and service UV systems in Oman against those references.
Buying GPH843T5L UV lamp Oman in Oman
UV Water Systems has supplied and serviced ultraviolet disinfection equipment across the Sultanate for more than 14 years, for hospitals, oil and gas sites, schools, hotels, food and beverage plants and villas. We stock germicidal lamps and ballasts in Muscat rather than ordering them in after a failure, so a plant that loses disinfection on a Sunday morning is not waiting three weeks for an air freight shipment.
Every lamp we supply is a named-manufacturer part with traceable 254 nm output data — the documentation health authority and HACCP auditors in Oman ask for. Our technicians cover Muscat, Sohar, Nizwa, Salalah and Duqm, and can carry out the lamp change, sleeve clean and UV intensity check as one visit under an annual maintenance contract.
Uniqueness View LLC is ISO 9001:2015 certified. Call +968 9763 7786 or email sales@waterfilteroman.com for stock availability, bulk pricing on service-contract quantities, or help identifying the correct lamp for a chamber you cannot find a part number on. Send us a photo of the old lamp and the chamber label and we will identify it for you.
See also our UV sterilizer systems, replacement quartz sleeves and electronic UV ballasts.



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