Philips ML - Revision history

Andrei.boiu: /* Features */

2021-10-05T17:15:53Z

Features

← Older revision		Revision as of 19:15, 5 October 2021
Line 11:		Line 11:
	*E27 base or E40 base		*E27 base or E40 base
	*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W) bulb		*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W) bulb
	*Color rendering index Ra of 49 to 62 (highest on lowest wattage lamps)		*Color rendering index Ra of 50 to 72 (highest on lowest wattage lamps)
	*230V operating voltage (highly sensitive to voltage)		*230V operating voltage (highly sensitive to voltage)
	*Typical lifetime of 10.000 (most lamps) to 13.000 hours (only 160W lamp)		*Typical lifetime of 10.000 (most lamps) to 13.000 hours (only 160W lamp)

Andrei.boiu: /* Features */

2021-10-05T17:15:16Z

Features

← Older revision		Revision as of 19:15, 5 October 2021
Line 11:		Line 11:
	*E27 base or E40 base		*E27 base or E40 base
	*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W) bulb		*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W) bulb
			*Color rendering index Ra of 49 to 62 (highest on lowest wattage lamps)
	*230V operating voltage (highly sensitive to voltage)		*230V operating voltage (highly sensitive to voltage)
	*Typical lifetime of 10.000 (most lamps) to 13.000 hours (only 160W lamp)		*Typical lifetime of 10.000 (most lamps) to 13.000 hours (only 160W lamp)

Andrei.boiu: /* Review */

2021-10-05T13:20:44Z

Review

← Older revision		Revision as of 15:20, 5 October 2021
Line 83:		Line 83:
	Slightly major drawbacks are the lamp's sensitivity to positioning and operating voltage, along with slightly lower than average service life, especially compared with modern lighting technology. The lamp's low efficiency is caused by the compromise of its internal construction. The warm light generated by the internal filament also comes with massive heat radiation, which is similar to typical tungsten lamps that were previously popular. It should be noted that, due to the lamp's construction, light output is not uniform, with noticeable segregation in colour and intensity between the center and tip of the lamp. Although this effect is not severe, it may be a slightly unpleasant effect in certain situations.		Slightly major drawbacks are the lamp's sensitivity to positioning and operating voltage, along with slightly lower than average service life, especially compared with modern lighting technology. The lamp's low efficiency is caused by the compromise of its internal construction. The warm light generated by the internal filament also comes with massive heat radiation, which is similar to typical tungsten lamps that were previously popular. It should be noted that, due to the lamp's construction, light output is not uniform, with noticeable segregation in colour and intensity between the center and tip of the lamp. Although this effect is not severe, it may be a slightly unpleasant effect in certain situations.

	The pleasant light is suited both as general lighting in homes as well as gardens or workshops. A good selection of lamps can be used if power consumption is not critical and a specific scene or effect is desirable. Unfortunately, especially in small spaces, the lamp can contribute to heating, which may be advantageous as well as undesirable, depending on application. Special care should be taken when cleaning the lamp as vibrations, dirt accumulation and improper handling can easily crack the bulb, especially on soft glass lamps. Any dirt present on the lamp may be trapped longer due to melting and subsequent adhesion to glass. This means that lamp cleaning has to be as thorough and careful as on old tungsten lamps. While the lamp has a very high output when started and slowly reduces on warm-up, with a corresponding change in light colour, it is not unpleasant. At the beginning most light is output by the internal incandescent ~~fillament~~ rather than the mercury discharge. Lamp restart in case of failure occurs in less than 2 minutes and is less unpleasant than on other high pressure discharge lamps.		The pleasant light is suited both as general lighting in homes as well as gardens or workshops. A good selection of lamps can be used if power consumption is not critical and a specific scene or effect is desirable. Unfortunately, especially in small spaces, the lamp can contribute to heating, which may be advantageous as well as undesirable, depending on application. Special care should be taken when cleaning the lamp as vibrations, dirt accumulation and improper handling can easily crack the bulb, especially on soft glass lamps. Any dirt present on the lamp may be trapped longer due to melting and subsequent adhesion to glass. This means that lamp cleaning has to be as thorough and careful as on old tungsten lamps. While the lamp has a very high output when started and slowly reduces on warm-up, with a corresponding change in light colour, it is not unpleasant. At the beginning most light is output by the internal incandescent filament rather than the mercury discharge. Lamp restart in case of failure occurs in less than 2 minutes and is less unpleasant than on other high pressure discharge lamps.

	This type of mercury vapour lamps were popular mostly before the oil crisis that ~~occured~~ in the 1970s. Many years have passed since use of this lamp was basically non ~~existant~~, meaning that stocks are not very large. Although the lamp could directly replace even less efficient tungsten or incandescent lamps, this market very rapidly diminished as soon as compact ~~flourescent~~ lamps with screw bases were made available. These had a much longer life, had no restriction on mounting, were highly energy efficient and had even better colour reproduction. There were few fixtures specifically designed for Philips ML lamps. They could operate on typical high pressure mercury vapour fixture but this was uncommon. There was a market for street-lighting in France, many decades ago, as the lamp offered a pleasant light and energy was quite cheap. Due to the lamp operating restrictions as well as simple use, free standing or hanging mounting were quite common, even if lighting efficiency was diminished.		This type of mercury vapour lamps were popular mostly before the oil crisis that occurred in the 1970s. Many years have passed since use of this lamp was basically non existent, meaning that stocks are not very large. Although the lamp could directly replace even less efficient tungsten or incandescent lamps, this market very rapidly diminished as soon as compact fluorescent lamps with screw bases were made available. These had a much longer life, had no restriction on mounting, were highly energy efficient and had even better colour reproduction. There were few fixtures specifically designed for Philips ML lamps. They could operate on typical high pressure mercury vapour fixture but this was uncommon. There was a market for street-lighting in France, many decades ago, as the lamp offered a pleasant light and energy was quite cheap. Due to the lamp operating restrictions as well as simple use, free standing or hanging mounting were quite common, even if lighting efficiency was diminished.

	== Operation ==		== Operation ==

Andrei.boiu: /* Review */

2021-10-05T13:20:20Z

Review

← Older revision		Revision as of 15:20, 5 October 2021
Line 81:		Line 81:
	These high pressure mercury vapour lamps are compact light sources that are viable for indoor as well as outdoor use. Good colour reproduction and a warm to neutral white colour appearance make these lamps suited for most applications except when efficiency or positioning limitations are taken into account. The lamp does not require any additional component, making the lamp very easy to install and operate.		These high pressure mercury vapour lamps are compact light sources that are viable for indoor as well as outdoor use. Good colour reproduction and a warm to neutral white colour appearance make these lamps suited for most applications except when efficiency or positioning limitations are taken into account. The lamp does not require any additional component, making the lamp very easy to install and operate.

	~~The only slight~~ drawbacks are the lamp's sensitivity to positioning and operating voltage, along with slightly lower than average service life, especially compared with modern lighting technology. The lamp's low efficiency is caused by the compromise of its internal construction. The warm light generated by the internal filament also comes with massive heat radiation, which is similar to typical tungsten lamps that were previously popular.		Slightly major drawbacks are the lamp's sensitivity to positioning and operating voltage, along with slightly lower than average service life, especially compared with modern lighting technology. The lamp's low efficiency is caused by the compromise of its internal construction. The warm light generated by the internal filament also comes with massive heat radiation, which is similar to typical tungsten lamps that were previously popular. It should be noted that, due to the lamp's construction, light output is not uniform, with noticeable segregation in colour and intensity between the center and tip of the lamp. Although this effect is not severe, it may be a slightly unpleasant effect in certain situations.

	The pleasant light is suited both as general lighting in homes as well as gardens or workshops. A good selection of lamps can be used if power consumption is not critical and a specific scene or effect is desirable. Unfortunately, especially in small spaces, the lamp can contribute to heating, which may be advantageous as well as undesirable, depending on application. Special care should be taken when cleaning the lamp as vibrations, dirt accumulation and improper handling can easily crack the bulb, especially on soft glass lamps. Any dirt present on the lamp may be trapped longer due to melting and subsequent adhesion to glass. This means that lamp cleaning has to be as thorough and careful as on old tungsten lamps. While the lamp has a very high output when started and slowly reduces on warm-up, with a corresponding change in light colour, it is not unpleasant. At the beginning most light is output by the internal incandescent fillament rather than the mercury discharge. Lamp restart in case of failure occurs in less than 2 minutes and is less unpleasant than on other high pressure discharge lamps.		The pleasant light is suited both as general lighting in homes as well as gardens or workshops. A good selection of lamps can be used if power consumption is not critical and a specific scene or effect is desirable. Unfortunately, especially in small spaces, the lamp can contribute to heating, which may be advantageous as well as undesirable, depending on application. Special care should be taken when cleaning the lamp as vibrations, dirt accumulation and improper handling can easily crack the bulb, especially on soft glass lamps. Any dirt present on the lamp may be trapped longer due to melting and subsequent adhesion to glass. This means that lamp cleaning has to be as thorough and careful as on old tungsten lamps. While the lamp has a very high output when started and slowly reduces on warm-up, with a corresponding change in light colour, it is not unpleasant. At the beginning most light is output by the internal incandescent fillament rather than the mercury discharge. Lamp restart in case of failure occurs in less than 2 minutes and is less unpleasant than on other high pressure discharge lamps.

Andrei.boiu: /* Manufacturing specificities */

2021-10-05T13:18:12Z

Manufacturing specificities

← Older revision		Revision as of 15:18, 5 October 2021
Line 105:		Line 105:

	== Manufacturing specificities ==		== Manufacturing specificities ==
	Philips has been releasing lamps for many decades. Lamps produced in the 70s and early 80s are probably not commonly found today. In the 90s and early 2000 Philips was manufacturing lamps in Holland and other countries, while in the last years they were doing the same thing in China. Quality was severely affected as, realistically speaking, there were some occasional lamp defects even in their Holland produced lamps due to average manufacturing quality. It should be noted that mercury vapour lamps were mass manufactured and considered low-cost products, meaning that quality was not paramount.		Philips has been releasing lamps for many decades. Lamps produced in the 70s and early 80s are probably not commonly found today. In the 90s and early 2000 Philips was manufacturing lamps in Holland and other countries, while in the last years they were doing the same thing in China. Quality was severely affected as, realistically speaking, there were some occasional lamp defects even in their Holland produced lamps due to average manufacturing quality. It should be noted that mercury vapour lamps were mass manufactured and considered low-cost products, meaning that quality was not paramount.

			Light uniformity on Philips ML lamps was also reduced by the preference for mounting the filament at the opposite end of the lamp base, rather than centrally around the discharge tube. This created a brownish, dirty lower appearance of the lamp, with pronounced yellowing and degradation of internal coating and less useful light directed downwards. The lack of uniformity also translated to lack of colour uniformity as the lamp's output was highly different at the center of the lamp compared with the tip. Overall, the Philips lamps were built very poorly with the only exception of the internal coating that was relatively decent, although far from the best.

	Until the manufacturing plants move to China, there were small differences in this product line as the 90s and early 2000s was using the same technology. Chinese built lamps have some slight efficiency improvements that trade off on light quality. The internal coating is thinner and has a different grain size with a potentially different powder mix, improving colour rendering more than what the datasheet suggests. However, the light contribution from the internal filament is reduced, reducing consumption but also slightly increasing the perceived light appearance. The colour temperature seems higher and the light has a slightly greenish appearance, making the lamp much less pleasing than competing Osram HWL lamps.		Until the manufacturing plants move to China, there were small differences in this product line as the 90s and early 2000s was using the same technology. Chinese built lamps have some slight efficiency improvements that trade off on light quality. The internal coating is thinner and has a different grain size with a potentially different powder mix, improving colour rendering more than what the datasheet suggests. However, the light contribution from the internal filament is reduced, reducing consumption but also slightly increasing the perceived light appearance. The colour temperature seems higher and the light has a slightly greenish appearance, making the lamp much less pleasing than competing Osram HWL lamps.

Andrei.boiu: /* Features */

2021-10-05T13:12:57Z

Features

← Older revision		Revision as of 15:12, 5 October 2021
Line 10:		Line 10:
	*Integrated internal ballast featuring an incandescent coil (filament)		*Integrated internal ballast featuring an incandescent coil (filament)
	*E27 base or E40 base		*E27 base or E40 base
	*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W)		*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W) bulb
	*230V operating voltage (highly sensitive to voltage)		*230V operating voltage (highly sensitive to voltage)
	*Typical lifetime of 10.000 (most lamps) to 13.000 hours (only 160W lamp)		*Typical lifetime of 10.000 (most lamps) to 13.000 hours (only 160W lamp)

Andrei.boiu at 13:12, 5 October 2021

2021-10-05T13:12:33Z

← Older revision		Revision as of 15:12, 5 October 2021
Line 3:		Line 3:
	\|style="vertical-align:top" \|		\|style="vertical-align:top" \|
	<div style="margin: 0; margin-right:10px; border: 1px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#F8F8FF; align:right;">		<div style="margin: 0; margin-right:10px; border: 1px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#F8F8FF; align:right;">
	Standard High Pressure Mercury Lamp ~~for general lighting~~ with ~~50W~~, ~~80W~~, ~~125W~~ (E27 base) and ~~125W, 250W, 400W, 700W, 1000W~~ (E40 base)		Standard Mixed Light Incandescent Tungsten and High Pressure Mercury Lamp with 100W, 160W, 250W (E27 base) and 250 and 500W (E40 base)

	== Features ==		== Features ==

Andrei.boiu at 13:11, 5 October 2021

2021-10-05T13:11:29Z

Andrei.boiu: /* Manufacturing specificities */

2021-10-05T13:01:58Z

Manufacturing specificities

← Older revision		Revision as of 15:01, 5 October 2021
Line 104:		Line 104:

	== Manufacturing specificities ==		== Manufacturing specificities ==
	Philips has been releasing lamps for many decades. Lamps produced in the 70s and early 80s are probably not commonly found today. In the 90s and early 2000 Philips was manufacturing lamps in Holland and other countries, while in the last years they were doing the same thing in China. Quality was ~~not~~ severely affected as, realistically speaking, there were some occasional lamp defects even in their Holland produced lamps due to average manufacturing quality. It should be noted that mercury vapour lamps were mass manufactured and considered low-cost products, meaning that quality was not paramount.		Philips has been releasing lamps for many decades. Lamps produced in the 70s and early 80s are probably not commonly found today. In the 90s and early 2000 Philips was manufacturing lamps in Holland and other countries, while in the last years they were doing the same thing in China. Quality was severely affected as, realistically speaking, there were some occasional lamp defects even in their Holland produced lamps due to average manufacturing quality. It should be noted that mercury vapour lamps were mass manufactured and considered low-cost products, meaning that quality was not paramount.

	Until the manufacturing plants move to China, there were small differences in this product line as the 90s and early 2000s was using the same technology. Chinese built lamps have some slight improvements that ~~leave some aspects to be desired as well~~. The internal coating is thinner and has a different grain size with a potentially different powder mix, improving colour rendering more than what the datasheet suggests~~. Lamp lumen maintenance and uniformity is improved due to a thinner coating that degrades slower and more uniformly~~. However, the ~~lamp~~ light ~~looks whitish-green rather than whitish-purple~~, ~~which might be unpleasant for some persons.~~		Until the manufacturing plants move to China, there were small differences in this product line as the 90s and early 2000s was using the same technology. Chinese built lamps have some slight efficiency improvements that trade off on light quality. The internal coating is thinner and has a different grain size with a potentially different powder mix, improving colour rendering more than what the datasheet suggests. However, the light contribution from the internal filament is reduced, reducing consumption but also slightly increasing the perceived light appearance. The colour temperature seems higher and the light has a slightly greenish appearance, making the lamp much less pleasing than competing Osram HWL lamps.

	~~Products manufactured by Philips were similar to General Electric~~ but ~~with a quality and consistency much above some East-European manufacturers in terms of colour rendering,~~ light ~~output and life~~. ~~However, Philips was manufacturing lamps with shorter lifetimes~~ and ~~poorer internal coatings than Osram ones~~, ~~even if some values specified in datasheets might not suggest much. These differences were maintained until~~ the ~~end of mercury vapour~~ lamp ~~production in the late 2010s. This Philips-~~Osram ~~lamp difference must be experienced in person. On the other side, Philips~~ lamps ~~were much more popular and are easier to find~~.

			Lamp lumen maintenance and uniformity is potentially improved due to a thinner coating and less heat being released inside the bulb, reducing coating degradation. However, due to the lamp even higher operating voltage, despite what the datasheet might suggest, the lamp is much quickly rendered useless, potentially prematurely, after only a few thousand hours, with unpleasant endless on-off cycles when powered. This behaviour is very common on the 160W Philips ML lamp as they were considered to be used in less critical installations as the higher rated 250 and 500W lamps. This means that the 160W lamp is clearly a very bad purchase, unless balanced by a very low purchasing cost.
	{{footnotes\|		{{footnotes\|
	#		#

Andrei.boiu: /* History */

2021-10-05T12:52:26Z

History

← Older revision		Revision as of 14:52, 5 October 2021
Line 97:		Line 97:

	== History ==		== History ==
	~~HPL-N~~ lamps are high pressure mercury vapour lamps ~~that have been produced~~, ~~with somewhat similar properties~~, since the ~~1950s~~. ~~The lamp's fluorescent coating technology dates back to around~~ the ~~end~~ of ~~1930s while modern~~ lamps ~~were essentially manufactured~~ as ~~early as 1970s~~ and ~~are a result~~ of ~~subsequent improvements up until that time~~. ~~The market for these~~ lamps ~~grew as industry~~ and ~~commercial activity recovered after~~ the ~~Second World War, meaning that research was justified by large sales~~.		ML lamps are slightly adapted high pressure mercury vapour lamps. They were originally designed to address the requirement of better colour reproduction compared with a bare mercury vapour lamp. While they did severly improve red output of the installation, efficiency was also reduced, since this additional light was created less efficiently with the thermal radiation of the internal fillament. Until the advent of suitable internal coatings on standard mercury vapour lamps, this mixed light lamp was also easy to use as there was no requirement for complex wiring, mounting and servicing of ballasts as well as lamps. As most light fixtures were using large wattage incandescent lamps, the Philips ML lamps were very easy to retrofit and for many decades this was a simple light upgrade. Of course, there were many improvements on lamp technology but the same benefits were kept along usability and lower maintenance due to less frequent lamp changing.

	~~The~~ lamp ~~technology was an improvement of previous lamps that used a clear envelope and had an alumino-silicate glass where~~ the ~~mercury discharge was constrained~~. ~~Colour reproduction was nonexistent, being so low as~~ to ~~render people~~ and ~~everything natural around them~~ as ~~being dead~~. ~~Increasing~~ the ~~pressure~~ and ~~temperature of the~~ mercury vapour ~~gas discharge~~ to ~~emit more useful~~ light ~~and operation in any position was possible only with~~ the advent of ~~quartz~~ discharge tubes~~. Colour reproduction was only slightly~~ improved but ~~lower wattage lamps~~ were ~~much more efficient. Up until late in production, the clear lamp was avoided except for street lighting and some industrial applications. Subsequently,~~ mercury vapour lamps ~~were heavily used in street lighting and industry. Colour rendering was the highest barrier to market success~~. ~~Improvements focused on colour reproduction but energy~~ efficiency ~~and reliability~~ increases were ~~areas with best~~ results.		Internal coatings were introduced on the entire lamp range in the 1980s although they were present even as early as 1950s on these mixed light lamp types. Coating were useful to make the beam pattern more uniform and there were many benefits to having a coating as the two internal light sources had slighly different patterns. Of course, coatings were useful if flourescent powders were used, but this increased the lamp cost and provided small improvements as light absorbtion, wear had to be very low. Also, light improvement was much reduced compared with a typically sized mercury vapour lamp due to less UV light being generated by the discharge tube. The advent of improved discharge tubes that were made of quartz instead of glass improved efficiency but results were not as large as on standard mercury vapour lamps. Major efficiency increases were, however, centered on lower powered lamps, as they could not be have the required balance of pressure and temperature to achive optimal results.

	~~Development~~ of ~~fluorescent~~ coatings ~~that emit red light made~~ the lamp ~~more desirable although good flourescent powders were mass produced and cheap only in late 1970s~~. The ~~lamps~~ itself ~~were running hot so fluorescent powders had~~ to ~~withstand temperature~~ and UV~~-C exposure stress for many years while also emitting more light~~ than ~~the coating powder absorbed~~. ~~The first generation powders had mild colour improvements but Yttrium Vanadate ones were highly successful and durable~~, ~~making the lamp suited even~~ for ~~some indoor illumination~~, ~~especially for deluxe lamps. Near~~ the ~~end of production deluxe lamps were very common~~ and ~~standard lamps such as~~ the ~~HPL-N were incorporating most developments specific to these top-of-~~the~~-line lamps. These improvements made high pressure~~ mercury vapour ~~lamps suited for industrial, commercial, street-lighting and even some occasional residential use~~.		Although important, the introduction of internal coatings did not have the same impact as on standard mercury vapour lamps. For many years the lamp had to be specifically designed to acomodate filaments as well as the heat being released. The coating itself does not contribute much to the light output as the mercury vapour discharge tube is smaller and has less UV output than a typically sized lamp. As a matter of fact, for a typical power rating, around half the wattage is used by the filament and the other half by the mercury vapour discharge tube. This is mostly due to the compromise of achieving a better colour reproduction than a typical standard mercury vapour lamp and this required more useful light released by the incandescent coil. Of course, better efficiency can be achieved with filaments that do not run as hot and with more light output from the mercury vapour discharge but most longtime manufactured lamps, including the Philips ML, aimed at better comfort and had to accept less efficiency.

	~~The energy crisis meant that clients demanded improvements and they were focused on improving these lamps, giving rise~~ to ~~derivatives such as metal-hallide lamps, with much~~ better colour reproduction ~~and lower energy consumption. Sodium lamps were improved, culminating in the high-pressure sodium lamps that, with their yellow-orange or golden glow, dominated exterior lighting. By late 1980s~~ mercury vapour ~~lamps where on a market share decline that lasted~~ more ~~than 25 years~~. ~~This~~ can be ~~attributed mostly to inertia in replacing fixtures~~ that ~~had a lifetime of around 15 years because new installations were~~ not ~~done after mid 1990s due to availability of compact or linear fluorescent lamps.~~

	~~These lamps were not intended for home or office use and they were seldomly used~~ as ~~such. Tungsten lamps had perfect colour reproduction~~ and ~~electric energy costs were very low. Even after~~ the ~~oil crisis of~~ the ~~early 1970s~~, ~~tungsten lamps were still cheap enough~~ and ~~convenient~~ to ~~be used for general lighting. Also, these lamps did no require any gear~~.

	== Manufacturing specificities ==		== Manufacturing specificities ==

← Older revision		Revision as of 15:11, 5 October 2021
Line 8:		Line 8:
	*Yttrium Vanadate internal coated bulb		*Yttrium Vanadate internal coated bulb
	*High pressure mercury vapour lamp with an internal quartz discharge tube		*High pressure mercury vapour lamp with an internal quartz discharge tube
	*E27 base or E40 base ~~(requires matching ballast)~~		*Integrated internal ballast featuring an incandescent coil (filament)
			*E27 base or E40 base
	*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W)		*Soft glass (100, 160 and 250W) or Hard glass (250 and 500W)
	*230V operating voltage (highly sensitive to voltage)		*230V operating voltage (highly sensitive to voltage)
Line 61:		Line 62:
	Generally, mercury vapour lamps were very durable but mixed lights, mercury vapour and tungsten, are quite sensitive. Strong, sudden shocks can damage the internal tungsten filament, permanently affecting the lamp. On each start-up the lamp is highly stressed as the tungsten filament operates at almost double the normal rated current which means that service life is strongly affected by switch on frequency. The lamp is impossible to service if any rupture of the filament occurs.		Generally, mercury vapour lamps were very durable but mixed lights, mercury vapour and tungsten, are quite sensitive. Strong, sudden shocks can damage the internal tungsten filament, permanently affecting the lamp. On each start-up the lamp is highly stressed as the tungsten filament operates at almost double the normal rated current which means that service life is strongly affected by switch on frequency. The lamp is impossible to service if any rupture of the filament occurs.

	All the above particular operating issues make the lamp slightly inconvenient to operate, even if the lamp itself is highly attractive to use and install and not an expensive purchase.		All the above particular operating issues make the lamp slightly inconvenient to operate, even if the lamp itself is highly attractive to use and install and not an expensive purchase. Failing lamps can be easily determined by the lengthened time of restart in case of power being cut off and then resumed. A longer than typical time and less definite starting after cooldown, meaning more failed attempts at restarting than 1 or 2, point to a worn of lamp that will soon be dead. Of course, as mentioned before, this should be tested with the same straight vertical position. However, as lamps age, they will be more sensitive to voltage, accumulated heat nearby the lamp than newer ones so actual service life can be severely reduced compared with what the datasheet may suggest.

	== Greatest features & flaws ==		== Greatest features & flaws ==
Line 82:		Line 83:
	The only slight drawbacks are the lamp's sensitivity to positioning and operating voltage, along with slightly lower than average service life, especially compared with modern lighting technology. The lamp's low efficiency is caused by the compromise of its internal construction. The warm light generated by the internal filament also comes with massive heat radiation, which is similar to typical tungsten lamps that were previously popular.		The only slight drawbacks are the lamp's sensitivity to positioning and operating voltage, along with slightly lower than average service life, especially compared with modern lighting technology. The lamp's low efficiency is caused by the compromise of its internal construction. The warm light generated by the internal filament also comes with massive heat radiation, which is similar to typical tungsten lamps that were previously popular.

	The pleasant light is suited both as general lighting in homes as well as gardens or workshops. A good selection of lamps can be used if power consumption is not critical and a specific scene or effect is desirable. Unfortunately, especially in small spaces, the lamp can contribute to heating, which may be advantageous as well as undesirable, depending on application. Special care should be taken when cleaning the lamp as vibrations, dirt accumulation and improper handling can easily crack the bulb, especially on soft glass lamps. Any dirt present on the lamp may be trapped longer due to melting and subsequent adhesion to glass. This means that lamp cleaning has to be as thorough and careful as on old tungsten lamps.		The pleasant light is suited both as general lighting in homes as well as gardens or workshops. A good selection of lamps can be used if power consumption is not critical and a specific scene or effect is desirable. Unfortunately, especially in small spaces, the lamp can contribute to heating, which may be advantageous as well as undesirable, depending on application. Special care should be taken when cleaning the lamp as vibrations, dirt accumulation and improper handling can easily crack the bulb, especially on soft glass lamps. Any dirt present on the lamp may be trapped longer due to melting and subsequent adhesion to glass. This means that lamp cleaning has to be as thorough and careful as on old tungsten lamps. While the lamp has a very high output when started and slowly reduces on warm-up, with a corresponding change in light colour, it is not unpleasant. At the beginning most light is output by the internal incandescent fillament rather than the mercury discharge. Lamp restart in case of failure occurs in less than 2 minutes and is less unpleasant than on other high pressure discharge lamps.

	This type of mercury vapour lamps were popular mostly before the oil crisis that occured in the 1970s. Many years have passed since use of this lamp was basically non existant, meaning that stocks are not very large. Although the lamp could directly replace even less efficient tungsten or incandescent lamps, this market very rapidly diminished as soon as compact flourescent lamps with screw bases were made available. These had a much longer life, had no restriction on mounting, were highly energy efficient and had even better colour reproduction. There were few fixtures specifically designed for Philips ML lamps. They could operate on typical high pressure mercury vapour fixture but this was uncommon. There was a market for street-lighting in France, many decades ago, as the lamp offered a pleasant light and energy was quite cheap. Due to the lamp operating restrictions as well as simple use, free standing or hanging mounting were quite common, even if lighting efficiency was diminished.		This type of mercury vapour lamps were popular mostly before the oil crisis that occured in the 1970s. Many years have passed since use of this lamp was basically non existant, meaning that stocks are not very large. Although the lamp could directly replace even less efficient tungsten or incandescent lamps, this market very rapidly diminished as soon as compact flourescent lamps with screw bases were made available. These had a much longer life, had no restriction on mounting, were highly energy efficient and had even better colour reproduction. There were few fixtures specifically designed for Philips ML lamps. They could operate on typical high pressure mercury vapour fixture but this was uncommon. There was a market for street-lighting in France, many decades ago, as the lamp offered a pleasant light and energy was quite cheap. Due to the lamp operating restrictions as well as simple use, free standing or hanging mounting were quite common, even if lighting efficiency was diminished.