From the very knowledgeable Jim Silvers on dating of certain Perfection Heaters:

"The globes with the oval with Perfection inside were the first.

The Firelight heaters were introduced in 1925 and the oval glass was used in the 1526–1527–1690—1691—1686–1692. This globe will not fit the newer models and are extremely hard to find. The Flame style globe started with the 1700 series of Firelight heaters in the 1930’s. Also used in the 735–750 and later heaters.

These have a larger diameter then the oval glassed globes"

The 500 series of Perfections started produced from around 1915 to 1925. When the Perfection series 1500 & 1600 series of heaters were introduced. Perfection continued to produce the #525 & # 510 model heaters until they were replaced with the #525-M in the late 1930’s . The #510 is a smaller sized heater I call a Junior. Stack is 7” not 8” like the standard size heaters. It’s 2” shorter. The fount is smaller in diameter but still uses the #500 wick and same flame spreader and gallery. These approximate dates come from old Perfection sales pamphlets."

"The #140-C would have the oval viewing window and small banner style ID tag. That model was produced by Perfection around 1910. The last year for any #100 - #200 series of heaters was 1916 when the #500-#600 series started. The #300-#400 series started in 1913 and ran for around 10 yrs. the #1500-1600 heaters started in 1925. The #1700 were in the 1930’s. If your original to the heater fount has a finger nut holding flame spreader in place it is before 1902. Oval viewing windows and small banner ID tag before 1910. Rectangular viewing window and Triangular window and used until 1930’s 1700 series."

"You will find all the Enameled heaters have Nickel trim parts. The first number in your #140 is the series of the heater. The next 2 numbers are the model.. So to keep it simple all #25 & #50 heaters are Black. #’s #30-#40-#60-#70 heaters would have Nickel trim. All Enameled heaters are Nickel trimmed. As a general rule all odd numbered series of heaters are black. The #100-#300-#500-#1500. The even numbered series of heaters are Enameled. #’s #200-#400-#600-#1600. You will find that the lower model numbered heaters had steel founts #25-#30 and higher model numbered heaters had Brass #40-#50-#60-#70."

Perfections first White Porcelain heaters was the #260 on far right. Next came the #760 on far left.  The second heater from left is the #1670 dated after 1925.
 The taller off white is a #330 not sure of date but before 1915.

GLOBE DATING INFORMATION:

Jim Siver:  "The globes with the oval with Perfection inside were the first.
The Firelight heaters were introduced in 1925 and the oval glass was used in the 1526–1527–1690—1691—1686–1692. This globe will not fit the newer models and are extremely hard to find. The Flame style globe started with the 1700 series of Firelight heaters in the 1930’s. Also used in the 735–750 and later heaters.
These have a larger diameter then the oval glassed globes

A COLOR & CHARACTERISTIC IDENTIFICATION GUIDE FOR PERFECTION OIL KEROSENE HEATERS

Information provided by Jim Silver

        (1)   Old odd numbers (56, 76 and 82)

        (2)   100 series: 3 different styles

        (3)   200 series:  Blue enameled - models 220–230–240–250–260–270

        (4)   300-400 series: Model numbers: 325,330,350,360,370,430,460,470

        (5)  1500-1600 series:

·        ALL BLACK HEATERS: 1525,1530,1550,1560

·        BLACK WITH GLASS – FIRELIGHT: Model 1526, 1527

·        BLACK & CREAM ENAMEL WITH GLASS: 1632

·        BROWN & CREAM ENAMEL: Model 1665

·        WHITE ENAMEL:  Model 1670      

·        GREEN & WHITE ENAMEL WITH GLASS: Model 1690

·        YELLOW & WHITE WITH GLASS:  Model 1691

·        GREEN ENAMEL WITH GLASS:  Model 1686

           (6) Art-Deco 1700 series: 

·        1700 black steel

·        1701 Black enamel—

·        1703 White enamel

·        1710 Black enamel new flame style glass

·        1712 Brown & White gale fount

·        1714 same as 1712 but with a brass fount

           (7) 500-600 series: Models 510,520,525,530,550,560. All black steel.

·        Models 630,650,660: Blue enamel

           (8)  700 series: 

·        Model 725: Black steel no viewing window

·        Model 730: Black steel with window

·        Model 735:  Black steel with Glass flame style

·        Model 750:  Brown & White and Brown & Cream Enamel with Glass Flame style

·        Models numbers 525 & 510 were being produced at same time as the 1500, 1600 & 1700 series. Model numbers 300-400 series are the small ‘pot belly’ styles.