Learn about UV lamp characteristics (A Comparison)
| Trait | Medium Pressure (MP) | Low Pressure (LP) & / or Amalgam (Low Pressure High Output-LPHO | Comments |
| Lamp | Evacuated to medium vacuum pressure | Evacuated to low vacuum pressure | Hence their names- this has nothing to do with the water pressure |
| Wavelength range (NB. UVC light has the highest germicidal properties and occurs approximately between 200nm-300nm) | Approx. 200nm-300nm (majority of output is between appros 240nm-280nm) | Monochromatic at 254nm | While all pathogens' DNA is denatured to some extent at 254nm, their DNA absorbs more broadly across much of the MP UV range. As such, pathogen DNA may be more broadly denatured by MP. This may explain why some studies have shown pathogens are less likely to repair their DNA damage (and therefore survive) after treatment by MP lamps. |
| Input Power | Typically 3000W-7000W | LP typically 50W-150W, LPHO typically 150W-500W | So, many more LP/LPHO lamps are required to emit the same amount of UVC energy as MP Lamps |
| Efficiency (conversion of electrical every to UVC energy) | Approximately 18% | Approximately 35% | So, approximately twice as much electrical energy required by MP lamps to emit the same UV energy as LP/LPHO lamps |
| Upshot of input power/ efficiency | 1 lamp | Equals approximately 10 LP lamps. Equals approximately 3-4 LPHO lamps | |
| Lamp life | Typically 8000 hours | Typically 12000-16000 hrs | |
| Working temperature of lamp | Many hundreds of degrees C | Less than 100 deg C | MP systems must constantly have water passing through them to keep the lamps cool. In some circumstances it may be possible for single-lamp LPHO systems (or multi-lamp LP systems) to cope with static water in the chamber for an extended period without overheating |
| Effect of water temperature on UVC output | None. Constant UV output independent of water temperature | LP-bell curve of UVC output (i.e lower UVC output at lower and higher temperatures, centred around a peak at about 20 deg C. LPHO- some susceptibility to water temperature, but not as dramatic as LP. | |
| Configuration | Chamber only | Channel or chamber | |
| Relative lamp price (approx per lamp) | "100" | "50" | While the price of LP & LPHO lamps is about 50% of MP, the number of extra lamps and labour costs of changing them will usually make MP systems much less expensive to maintain in terms of parts and labour. |
| Relative running (power) costs- approx | "100" | "50" | LP & LPHO consume about 50% of power compared to MP systems. This holds, regardless of the number of lamps per systems. |
| Relative cost of ownership summary |
-higher capital costs -higher cost per lamp -higher power costs -lower maintenance/labour costs |
-lower capital costs -lower cost per lamp -lower power costs -higher maintenance/labour costs |
As a general rule, the larger the system: -less capital cost difference between LP/LPHO & MP systems -lamp and labour costs will increasingly be more expensive for LP/LPHO than MP -power costs will increasingly become more expensive for MP than LP/LPHO |