Dryer Sizing Guide Lines - HDI, Inc.

1 C-69 Granada St., Alhambra Bayam n, PR 00957-2328 Tel. (787) 269-3278 Fax (787) 778-0864 Email: Dryer Sizing Guide Lines Hygroscopic Materials: Dryer : Utilize 1 cfm of dry air per pound of material per hour (eg.: 100 lbs/hr = 100 cfm Dryer ). Note that one (1) cfm per pound of material provides system flexibility for various process applications and helps compensate for process variables. In some cases (with dedicated service), a lower ratio of air to material can be used. Always consult your material or dehumidifier supplier for such cases. Also for high altitude locations (above 1,500 ft)( ), consult your dehumidifier supplier, since air is thinner and the application may need more air flow than at sea level. drying HOPPER Sizing : To calculate the size of the drying hopper you will need to know: 1) Material type 2) Material consumption (lbs/hr): If you do not know this, follow this simple steps: a) Weight a complete shot (parts + runner if applicable) from your molding machine, (ounces).

2 B) Read from the machine control the total cycle time in seconds. c) You have: material / time => ounces / seconds. Convert to lbs/hr by multiplying by 225. 3) The following formula: Now with the use of the table below and this formula you can compute your drying hopper size: (Material consumption (lbs/hr) * Virgin Material drying time * Virgin Material percentage) / Virgin Material Bulk Density + (Material consumption (lbs/hr) * Regrind Material drying time * Regrind Material percentage) / Regrind Material Bulk Density IF YOU ARE NOT USING REGRIND THE FORMULA SIMPLIFIES TO: Material consumption (lbs/hr) * Virgin Material drying time / Virgin Material Bulk Density v This will give you a drying hopper size in cubic foot. If the number calculated lies between two different sizes of drying hoppers, ALWAYS select the larger one. v If you will run more than one material with the same Dryer on the same machine with similar through puts, calculate the drying hopper for all of them and select the larger one.

3 V If you need to take samples of dried material regularly, calculate how much material you take out in one (1) hour and ADD that amount to the total through put (lbs/hr) before computing Dryer and drying Hopper sizes. v Insulate drying hopper and (to-process) air hose for energy savings and better temperature control. v Never insulate the return hose to the Dryer . v Always use After-cooler if processing ( drying ) at or above 250oF (121oC). v Keep Dryer filters clean for best performance. v Change Dryer desiccant as required by process conditions and Dryer usage. v Glass Fillers will reduce the drying time. v Graphite, Talc or Carbon Black Fillers will extend the drying time. On the Table below, you can find typical values for various virgin (V) and regrind (R) materials. Material Hygro - drying drying Bulk Densities scopic ? Hours Temp (F) lb/cu. ft. R V R V ABS (Molding) Yes 2 4 190-200 32 42 ABS (Extrusion) Yes 2 4 190-200 25 42 ABS/PC Yes 4 5 220-230 32 40 ABS/PVC Yes 2 3 160-170 35 45 ACETAL (Copolymer) Yes 2 3 200-220 35 40 ACETAL (Homopolymer) NO (1) 1 2 200-220 35 40 ACRYLIC Yes 2 3 170-190 36 42 CA (Acetate) Yes 2 3 160-180 32 38 CAB Yes 2 3 160-180 33 39 CAP Yes 2 3 160-180 34 40 EVOH Yes 2 3 195-225 32 36 HDPE NO (1) 1 2 160-180 28 35 HDPE w 3% Black Yes 3 4 160-180 26 34 HDPE w 40% Black Yes 4 5 160-180 26 34 HDPE cable grade Yes 5 6 140-150 28 35 IONOMER Yes 7 8 150-160 36 44 LCP Yes 3 4 300-310 46 50 LDPE NO (1) 1 2 160-180 24 32 LDPE w 3% Black Yes 3 4 160-180 24 32 LDPE w 40% Black Yes 4 5 160-180 24 32 NITRILE Yes 5 6 160-180 32 40 NYLON 6, 6/6, 6/12 Yes 5 6 160-180 35 41 NYLON 11, 12 Yes 5 6 160-180 35 41 NYLON (Amorfo) Yes 4 5 170-180 36 42 NYLON (transparent)

4 Yes 4 5 180-190 35 41 OSA Yes 2 3 180-190 36 42 PBT Yes 2 3 250-270 44 52 PBT/PET Yes 4 5 350-370 44 50 PC Yes 3 4 250-270 36 40 PC/PBT/E Yes 3 4 220-230 38 42 PCS Yes 2 3 220-230 34 38 PCTA Yes 3 4 160-180 44 52 PEEK Yes 3 4 300-320 44 52 PEEK (reinforced) Yes 3 4 300-320 44 52 PEM Yes 6 7 300-310 46 52 PES Yes 3 4 300-320 46 52 PES (easy flow) Yes 3 4 300-320 46 52 PET (Extrusion) Yes 4 5 320-350 46 52 PET (Molding) Yes 2 4 250-270 46 54 PET (Beverages) Yes 5 6 340-350 46 52 PETG Yes 3 4 140-150 40 50 POLYARYLATE Yes 5 6 250-260 44 50 POLYSULFONE Yes 4 5 250-260 44 50 POLYURETHANE Yes 2 3 180-200 42 48 PP NO (1) 1 2 170-190 27 33 PPA Yes 6 7 175-180 40 48 PPC Yes 3 4 260-270 44 50 PPO (noryl) Yes 2 4 200-250 44 50 PPS Yes 3 4 280-290 44 50 PPS (40% glass) Yes 3 4 300-320 44 50 PS (styrene) GPPS NO (1) 1 2 180-190 27 35 HIPS Yes 1 2 180-190 27 35 PTMT Yes 2 3 210-220 44 50 PVC (flexible) NO (1) 1 2 180-190 34 48 PVC (rigid) NO (1) 1 2 180-190 32 50 SAN Yes 3 4 180-190 32 40 SAN (modified) Yes 3 6 160-180 36 42 SMA Yes 2 3 200-210 32 38 TPE Yes 2 3 210-220 42 48 TPR (easy flow) Yes 2 3 150-170 42 48 XT Yes 3 4 170-190 36 40 (1) Hot air Dryer recommended; dehumidifying Dryer s desiccant beds may become saturated.

5 (2) Use shorter drying time listed for non-critical injection molding applications. (3) Use the longer drying time listed for critical molding and extrusion applications.